Consistency Refactoring

All 6 consistency review items have been resolved, verified with new
unit tests, automated test suites, and clean example builds.

- **Fixed `Goto` Duration Bug**: In
  [`turtle-lib/src/command_behavior.rs`](file:///home/dietrich/Projekte/Source/turtlers/turtle-lib/src/command_behavior.rs),
  mapped Cartesian target coordinates to screen space (`vec2(target.x,
  -target.y)`) before calculating $\Delta x$ and $\Delta y$ in
  `animation_duration`.
- **Unit Test**: Added `test_goto_duration_cartesian_inversion` testing
  that moving from screen $(0, 100)$ (Cartesian $(0, -100)$) to
  Cartesian $(0, 100)$ computes duration based on the actual 200px
  Euclidean distance ($2.0\text{s}$ at $100\text{ px/s}$).

- **Stored `Degrees`**: Updated `TurtleCommand::SetHeading(Degrees)` in
  [`turtle-lib/src/commands.rs`](file:///home/dietrich/Projekte/Source/turtlers/turtle-lib/src/commands.rs)
  to store user degrees directly ($0^\circ = \text{East}$, $90^\circ =
  \text{North}$), matching `Turn(Degrees)` and `Circle { angle: Degrees
  }`.
- **Deferred Screen-Space Conversion**: Converted to internal screen
  radians (`normalize_angle(-heading.as_radians().value())`) inside
  `apply_to_params` in
  [`turtle-lib/src/command_behavior.rs`](file:///home/dietrich/Projekte/Source/turtlers/turtle-lib/src/command_behavior.rs).
- **Instant Duration**: Maintained instant transition ($0.01\text{s}$
  minimum) in `animation_duration`.
- **Unit Test**: Added `test_set_heading_degrees_and_instant_duration`
  verifying $90^\circ$ maps to North ($-\frac{\pi}{2}$ in screen space),
  $0^\circ$ to East ($0$), $270^\circ$ to South ($+\frac{\pi}{2}$), and
  duration is $0.01\text{s}$.

- **Enhanced `Length` Type**: Expanded
  [`turtle-lib/src/general/length.rs`](file:///home/dietrich/Projekte/Source/turtlers/turtle-lib/src/general/length.rs)
  with `new()`, `value()`, `Neg`, `PartialOrd`, and conversion
  implementations (`From<f32>`, `From<f64>`, `From<i32>`, `From<i16>`,
  `From<usize>`).
- **Adopted Across API**:
  - `TurtleCommand::Move(Length)` in `commands.rs`.
  - `TurtleCommand::Circle { radius: Length, ... }` in `commands.rs`.
  - `forward<T: Into<Length>>` and `backward<T: Into<Length>>` in
    [`turtle-lib/src/builders.rs`](file:///home/dietrich/Projekte/Source/turtlers/turtle-lib/src/builders.rs).
  - `circle_left`, `circle_right` accept `radius: impl Into<Length>`.
  - Kept stroke attribute `pen_width` as `Precision` (`f32`).
- **Unit Test**: Added `test_length_conversions_and_negation` in
  `general::length`.

- **Removed Duplicate Alias**: Removed `all_animations_complete(&self)`
  from `TurtleApp` in
  [`turtle-lib/src/lib.rs`](file:///home/dietrich/Projekte/Source/turtlers/turtle-lib/src/lib.rs);
  updated call in
  [`turtle-lib/src/export.rs`](file:///home/dietrich/Projekte/Source/turtlers/turtle-lib/src/export.rs)
  to use canonical `is_complete(&self)`.
- **Corrected
  [`README.md`](file:///home/dietrich/Projekte/Source/turtlers/README.md)**:
  - `plan.goto(...)` $\rightarrow$ `plan.go_to(...)`
  - `plan.set_color(...)` $\rightarrow$ `plan.set_pen_color(...)`
  - `create_turtle()` $\rightarrow$ `create_turtle_plan()`
- **Corrected
  [`AGENTS.md`](file:///home/dietrich/Projekte/Source/turtlers/AGENTS.md)**:
  - `create_turtle()` $\rightarrow$ `create_turtle_plan()` in Threading
    Pattern.

- **Unified on `1000.0`**:
  - Updated
    [`README.md`](file:///home/dietrich/Projekte/Source/turtlers/README.md)
    lines 9, 108, 109 to state `speed >= 1000` is Instant and `speed <
    1000` is Animated.
  - Updated
    [`turtle-lib/examples/circle_test.rs`](file:///home/dietrich/Projekte/Source/turtlers/turtle-lib/examples/circle_test.rs)
    to use `turtle.set_speed(1000)`.

- **Renamed Examples**:
  - `turtle-lib/examples/stern.rs` $\rightarrow$
    [`turtle-lib/examples/star.rs`](file:///home/dietrich/Projekte/Source/turtlers/turtle-lib/examples/star.rs)
  - `turtle-lib/examples/nikolaus.rs` $\rightarrow$
    [`turtle-lib/examples/house_of_nikolaus.rs`](file:///home/dietrich/Projekte/Source/turtlers/turtle-lib/examples/house_of_nikolaus.rs)
- **Translated Functions & Parameters**:
  - `house_of_nikolaus.rs`: Translated `nikolausquadrat` $\rightarrow$
    `house_square`, `nikolausdiag` $\rightarrow$ `house_diagonal`,
    `nikolausdach2` $\rightarrow$ `house_roof`, parameter `groesse`
    $\rightarrow$ `size`. Added doc comment explaining the Eulerian path
    puzzle.
  - `breadboard.rs`: Translated `pin_reihe` $\rightarrow$ `pin_row`,
    `pin_spalte` $\rightarrow$ `pin_column`, `pin_seite` $\rightarrow$
    `pin_side`, parameter `anzahl` $\rightarrow$ `count`,
    `anzahl_reihen` $\rightarrow$ `row_count`. Added `#[cfg(feature =
    "svg")]` to helper functions to eliminate dead-code warnings when
    SVG feature is not enabled.
- **Translated UI Text & Print Messages**:
  - `"Drücke E für SVG-Export"` $\rightarrow$ `"Press E for SVG export"`
  - `"SVG exportiert nach test.svg"` $\rightarrow$ `"SVG exported to
    test.svg"`
  - `"Fehler beim Export: {:?}"` $\rightarrow$ `"Export error: {:?}"`
  - `"SVG-Export ist nicht aktiviert..."` $\rightarrow$ `"SVG export is
    not enabled..."`
  - Translated module doc in `export_svg.rs`.
- **Updated
  [`README.md`](file:///home/dietrich/Projekte/Source/turtlers/README.md)**
  example lists and CLI commands to reference `star` and
  `house_of_nikolaus`.

---

- `cargo test --package turtle-lib`:
  - 13 unit tests passed (including 3 new targeted unit tests)
  - 34 doctests passed (1 ignored internal helper)
- `cargo check --workspace --all-targets --all-features`: Passed with 0
  errors.
- `cargo check --examples --package turtle-lib --all-features`: All 30
  examples compiled cleanly with 0 errors.
- `cargo clippy --package turtle-lib -- -Wclippy::pedantic
  -Aclippy::cast_precision_loss -Aclippy::cast_sign_loss
  -Aclippy::cast_possible_truncation`: Passed with 0 errors.

README.md

@@ -6,7 +6,7 @@ A modern turtle graphics library for Rust built on [Macroquad](https://macroquad
 
 - 🎨 **Simple Builder API**: Chain commands like `forward(100).right(90)`
 - ⚡ **Smooth Animations**: Tweening support with easing functions and live fill preview
-- 🚀 **Instant Mode**: Execute commands immediately without animation (speed ≥ 999)
+- 🚀 **Instant Mode**: Execute commands immediately without animation (speed ≥ 1000)
 - 🎯 **High-Quality Rendering**: Complete Lyon tessellation pipeline with GPU acceleration
 - 🫟 **Multi-Contour Fills**: Automatic hole detection with EvenOdd fill rule - draw cheese with holes!
 - 📐 **Self-Intersecting Paths**: Stars, complex shapes - all handled correctly
@@ -99,14 +99,14 @@ plan.begin_fill();
 plan.end_fill();  // Auto-closes and applies fill
 
 // Appearance
-plan.set_color(RED);
+plan.set_pen_color(RED);
 plan.set_pen_width(5.0);
 plan.hide();
 plan.show();
 
 // Speed control (dynamic)
-plan.set_speed(100);  // Animated mode (< 999)
-plan.set_speed(1000); // Instant mode (>= 999)
+plan.set_speed(100);  // Animated mode (< 1000)
+plan.set_speed(1000); // Instant mode (>= 1000)
 
 // Turtle shapes
 plan.shape(ShapeType::Triangle);
@@ -136,7 +136,7 @@ let mut plan = create_turtle_plan();
 // Fast initial positioning (instant mode)
 plan.set_speed(1000);
 plan.pen_up();
-plan.goto(vec2(-100.0, -100.0));
+plan.go_to(vec2(-100.0, -100.0));
 
 // Slow animated drawing
 plan.set_speed(50);
@@ -219,7 +219,7 @@ You can also export SVG programmatically from your code:
 use turtle_lib::*;
 
 // Create your drawing
-let mut plan = create_turtle();
+let mut plan = create_turtle_plan();
 plan.forward(100).right(90).forward(100);
 
 // Create app
@@ -252,8 +252,8 @@ cargo run --example square
 cargo run --example koch
 cargo run --example shapes
 cargo run --example yinyang
-cargo run --example stern
-cargo run --example nikolaus
+cargo run --example star
+cargo run --example house_of_nikolaus
 
 # SVG export example (requires --features svg)
 cargo run --example export_svg --features svg
@@ -274,8 +274,8 @@ RUST_LOG=turtle_lib=debug cargo run --example logging_example
 - **square.rs**: Basic square drawing
 - **koch.rs**: Koch snowflake fractal
 - **shapes.rs**: Demonstrates different turtle shapes
-- **stern.rs**: Star pattern drawing
-- **nikolaus.rs**: Nikolaus (Santa) drawing
+- **star.rs**: Star pattern drawing
+- **house_of_nikolaus.rs**: House of Nikolaus (Eulerian path puzzle)
 
 #### Fill Examples
 
@@ -297,7 +297,7 @@ RUST_LOG=turtle_lib=debug cargo run --example logging_example
 ### Basic Fill
 
 ```rust
-let mut plan = create_turtle();
+let mut plan = create_turtle_plan();
 plan.set_fill_color(RED);
 plan.begin_fill();
 
@@ -321,7 +321,7 @@ plan.circle_left(90.0, 360.0, 72);
 
 // pen_up() closes current contour
 plan.pen_up();
-plan.goto(vec2(0.0, -30.0));
+plan.go_to(vec2(0.0, -30.0));
 
 // pen_down() starts new contour
 plan.pen_down();