refactor(modules): rename home module to draw, restore first-tab order

The Home tab was already titled "Draw"; rename the module to match:
folder modules/home → modules/draw, HomeModule → DrawModule, id "home"
→ "draw". The inner draw/ command folder is kept (modules::draw::draw).

Update build.rs PRIORITY ("home" → "draw") so the tab returns to the
front of the ribbon; registry.rs regenerates accordingly.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/modules/draw/inquiry/area.rs

@@ -0,0 +1,88 @@
+// AREA command — compute area and perimeter of a polygon picked point by point.
+// Press Enter to close and calculate.
+
+use glam::Vec3;
+
+use crate::command::{CadCommand, CmdResult};
+use crate::scene::model::wire_model::WireModel;
+
+pub struct AreaCommand {
+    points: Vec<Vec3>,
+}
+
+impl AreaCommand {
+    pub fn new() -> Self {
+        Self { points: vec![] }
+    }
+}
+
+impl CadCommand for AreaCommand {
+    fn name(&self) -> &'static str {
+        "AREA"
+    }
+
+    fn prompt(&self) -> String {
+        if self.points.is_empty() {
+            "AREA  Specify first corner point (Enter to cancel):".into()
+        } else {
+            format!(
+                "AREA  Specify next point ({} picked, Enter to calculate):",
+                self.points.len()
+            )
+        }
+    }
+
+    fn on_point(&mut self, pt: Vec3) -> CmdResult {
+        self.points.push(pt);
+        CmdResult::NeedPoint
+    }
+
+    fn on_enter(&mut self) -> CmdResult {
+        if self.points.len() < 3 {
+            return CmdResult::Cancel;
+        }
+        // Shoelace formula in the world XY plane.
+        let n = self.points.len();
+        let mut area_sum = 0.0f32;
+        let mut perimeter = 0.0f32;
+        for idx in 0..n {
+            let a = self.points[idx];
+            let b = self.points[(idx + 1) % n];
+            area_sum += a.x * b.y - b.x * a.y;
+            perimeter += (b - a).length();
+        }
+        let area = (area_sum * 0.5).abs();
+        let msg = format!("Area = {area:.4},  Perimeter = {perimeter:.4}");
+        CmdResult::Measurement(msg)
+    }
+
+    fn on_mouse_move(&mut self, pt: Vec3) -> Option<WireModel> {
+        if self.points.is_empty() {
+            return None;
+        }
+        let mut pts: Vec<[f32; 3]> = self.points.iter().map(|p| [p.x, p.y, p.z]).collect();
+        pts.push([pt.x, pt.y, pt.z]);
+        pts.push([self.points[0].x, self.points[0].y, self.points[0].z]);
+        Some(WireModel {
+            name: "area_preview".into(),
+            points: pts,
+            color: WireModel::CYAN,
+            selected: false,
+            pattern_length: 0.0,
+            pattern: [0.0; 8],
+            line_weight_px: 1.0,
+            snap_pts: vec![],
+            tangent_geoms: vec![],
+            aci: 0,
+            key_vertices: vec![],
+            aabb: WireModel::UNBOUNDED_AABB,
+            plinegen: true,
+            vp_scissor: None,
+            fill_tris: vec![],
+        })
+    }
+}
+
+
+// ── Autocomplete registry ─────────────────────────────────
+inventory::submit!(crate::command::CommandRegistration { names: &["AREA"] });  // AreaCommand