fix(simulation): replace f32 fields in generator with integer types

BlockPlacement.street_width_factor (f32) → street_width_bps (u16,
basis points where 10000 = 1.0×). BlockSkeleton.density (f32) →
density_pct (u8, 0–100 percentage). Eliminates latent f32
non-determinism per D-010 principle 1.

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

server/src/simulation/generator.rs

@@ -301,8 +301,9 @@ pub struct BlockPlacement {
     pub offset: (i16, i16),
     /// Rotation in 15° increments (0–3, max 45°).
     pub rotation_steps: u8,
-    /// Street width multiplier (0.75–2.0; default 1.0 = 4 visual tiles).
-    pub street_width_factor: f32,
+    /// Street width in basis points (10000 = 1.0×, range 7500–20000 for 0.75–2.0×).
+    /// Default 10000 = 4 visual tiles. Uses integer to avoid f32 non-determinism (D-010).
+    pub street_width_bps: u16,
 }
 
 /// Single block within a district's 4×4 block grid.
@@ -319,8 +320,9 @@ pub struct BlockSkeleton {
     pub era: Era,
     pub era_modifications: Vec<EraModification>,
     pub era_cause: Option<EraCause>,
-    /// Build density scalar (0.0 = open/empty, 1.0 = fully built-up).
-    pub density: f32,
+    /// Build density percentage (0 = open/empty, 100 = fully built-up).
+    /// Integer to avoid f32 non-determinism (D-010).
+    pub density_pct: u8,
     pub landmark: Option<LandmarkSlot>,
 }