Feat: ROADMAP Phase 1-5 batch — trim/extend, plot scale, viewport UX, mline caps, table alignment

- TRIM/EXTEND: Ray and XLine entities supported as cutting boundaries and trim targets;
  trim results in Ray→Line/Ray, XLine→Ray/Ray or Line; hover preview added
- Plot scale override: Fit/1:1/1:2/1:5/1:10/1:20/1:50/1:100/2:1 buttons added to Page Setup
  panel; PageSetupCommit applies scale to PlotSettings
- Viewport UX: locked viewport gets orange border; selected viewport gets white border
- Named view → viewport assignment: Choice dropdown in properties panel copies
  view_target/direction/height to the viewport entity
- MLine caps: perpendicular start/end cap lines added for open (non-closed) MLines
- Wipeout polygon grips: boundary vertices become editable grips when clipping_enabled+Polygonal;
  world→pixel back-projection on drag
- Table cell alignment: CellStyle.alignment (1-9) drives left/center/right + top/middle/bottom
  text positioning; cxf::measure_text() helper added
- New commands/features: DIMCONTINUE (DCO), DIMBASELINE (DBA), TOLERANCE (TOL), TABLE,
  ATTDEF, ATTEDIT, ATTDISP, BREAKATPOINT (BAP), PLOTWINDOW (PW), MLINE (ML);
  DIMSTYLE/DIMCURRENT/CLAYER/LTSCALE/CELTSCALE/SCALETEXT/XDATA/UCSICON/REGEN/DRAWORDER extended
- PLINE arc mode: A/L/CLOSE text input, bulge computation, arc preview
- Warning cleanup: removed unused imports and unreachable patterns

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/modules/home/draw/attdef.rs

@@ -0,0 +1,137 @@
+// ATTDEF command — define a block attribute (AttributeDefinition entity).
+//
+// Workflow (command-line only):
+//   1. Text: Enter attribute tag    (required, no spaces)
+//   2. Text: Enter attribute prompt (optional — press Enter to use tag)
+//   3. Text: Enter default value    (optional — press Enter for blank)
+//   4. Point: Click insertion point
+
+use acadrust::entities::AttributeDefinition;
+use acadrust::types::Vector3;
+use acadrust::EntityType;
+use glam::Vec3;
+
+use crate::command::{CadCommand, CmdResult};
+use crate::scene::wire_model::WireModel;
+
+enum Step {
+    Tag,
+    Prompt { tag: String },
+    Default { tag: String, prompt: String },
+    Insertion { tag: String, prompt: String, default: String },
+}
+
+pub struct AttdefCommand {
+    step: Step,
+    /// Text height in world units.
+    height: f64,
+}
+
+impl AttdefCommand {
+    pub fn new() -> Self {
+        Self { step: Step::Tag, height: 0.2 }
+    }
+}
+
+impl CadCommand for AttdefCommand {
+    fn name(&self) -> &'static str { "ATTDEF" }
+
+    fn prompt(&self) -> String {
+        match &self.step {
+            Step::Tag         => "ATTDEF  Enter attribute tag (no spaces):".into(),
+            Step::Prompt { tag } => format!("ATTDEF  Enter prompt for '{tag}' (Enter=use tag):"),
+            Step::Default { tag, .. } => format!("ATTDEF  Enter default value for '{tag}' (Enter=blank):"),
+            Step::Insertion { tag, .. } => format!("ATTDEF  Specify insertion point for '{tag}':"),
+        }
+    }
+
+    fn wants_text_input(&self) -> bool {
+        !matches!(self.step, Step::Insertion { .. })
+    }
+
+    fn on_text_input(&mut self, text: &str) -> Option<CmdResult> {
+        match &self.step {
+            Step::Tag => {
+                let tag = text.trim().replace(' ', "_");
+                if tag.is_empty() {
+                    return Some(CmdResult::NeedPoint);
+                }
+                self.step = Step::Prompt { tag };
+                Some(CmdResult::NeedPoint)
+            }
+            Step::Prompt { tag } => {
+                let tag = tag.clone();
+                let prompt = if text.trim().is_empty() { tag.clone() } else { text.trim().to_string() };
+                self.step = Step::Default { tag, prompt };
+                Some(CmdResult::NeedPoint)
+            }
+            Step::Default { tag, prompt } => {
+                let tag = tag.clone();
+                let prompt = prompt.clone();
+                let default = text.trim().to_string();
+                self.step = Step::Insertion { tag, prompt, default };
+                Some(CmdResult::NeedPoint)
+            }
+            Step::Insertion { .. } => None,
+        }
+    }
+
+    fn on_point(&mut self, pt: Vec3) -> CmdResult {
+        if let Step::Insertion { tag, prompt, default } = &self.step {
+            let mut attdef = AttributeDefinition {
+                tag: tag.clone(),
+                prompt: prompt.clone(),
+                default_value: default.clone(),
+                insertion_point: Vector3::new(pt.x as f64, pt.z as f64, pt.y as f64),
+                height: self.height,
+                ..Default::default()
+            };
+            attdef.common.layer = "0".into();
+            CmdResult::CommitAndExit(EntityType::AttributeDefinition(attdef))
+        } else {
+            CmdResult::NeedPoint
+        }
+    }
+
+    fn on_enter(&mut self) -> CmdResult {
+        match &self.step {
+            Step::Tag => CmdResult::Cancel,
+            // Treat Enter as empty text input for prompt/default steps.
+            Step::Prompt { tag } => {
+                let tag = tag.clone();
+                self.step = Step::Default { tag: tag.clone(), prompt: tag };
+                CmdResult::NeedPoint
+            }
+            Step::Default { tag, prompt } => {
+                let (tag, prompt) = (tag.clone(), prompt.clone());
+                self.step = Step::Insertion { tag, prompt, default: String::new() };
+                CmdResult::NeedPoint
+            }
+            Step::Insertion { .. } => CmdResult::Cancel,
+        }
+    }
+
+    fn on_mouse_move(&mut self, pt: Vec3) -> Option<WireModel> {
+        if !matches!(self.step, Step::Insertion { .. }) {
+            return None;
+        }
+        // Show a small cross at the insertion point.
+        let d = 0.15_f32;
+        Some(WireModel {
+            name: "attdef_preview".into(),
+            points: vec![
+                [pt.x - d, pt.y, pt.z], [pt.x + d, pt.y, pt.z],
+                [f32::NAN, 0.0, 0.0],
+                [pt.x, pt.y, pt.z - d], [pt.x, pt.y, pt.z + d],
+            ],
+            color: WireModel::CYAN,
+            selected: false,
+            pattern_length: 0.0,
+            pattern: [0.0; 8],
+            line_weight_px: 1.0,
+            snap_pts: vec![],
+            tangent_geoms: vec![],
+            key_vertices: vec![],
+        })
+    }
+}