Title screen, pause menu, settings dialog and savegames

- title screen (continue/new/load/settings/help) and Esc pause menu
- settings: language & sound, camera, graphics, game, rebindable keys;
  stored in localStorage and in every savegame (always applied on load)
- savegames as JSON (.dcsave): download, load via file picker or drag & drop
- autosave to localStorage every 2 minutes and when the tab is hidden/closed
- configurable wall detail, light count, interface size, game speed, hints
- audio behind a cargo feature so native tests run (cargo test --no-default-features)
- savegame round-trip test

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/render3d.rs

@@ -8,6 +8,7 @@ use crate::map::*;
 use macroquad::miniquad::{BlendFactor, BlendState, BlendValue, Comparison, Equation, PipelineParams, UniformDesc, UniformType};
 use macroquad::models::{Mesh, Vertex};
 use macroquad::prelude::*;
+use serde::{Deserialize, Serialize};
 
 pub const WALL_H: f32 = 0.95;
 const CHUNK: i32 = 16;
@@ -15,11 +16,11 @@ const NCH: i32 = MW as i32 / CHUNK;
 pub const MAX_LIGHTS: usize = 24;
 const ATLAS_W: f32 = 256.0;
 const ATLAS_H: f32 = 80.0;
-const WALL_SUB: usize = 3; // subdivisions per wall face edge
 const DISP_AMP: f32 = 0.11; // wall surface irregularity
 
 // ------------------------------------------------------------------ camera
 
+#[derive(Clone, Serialize, Deserialize)]
 pub struct Cam {
     pub tx: f32, // look-at target on the ground (world x)
     pub tz: f32, // look-at target on the ground (world z = map y)
@@ -411,7 +412,7 @@ fn edge_pts(a: Vec3, b: Vec3, n: usize) -> Vec<Vec3> {
         .collect()
 }
 
-fn build_chunk(map: &Map, amb: &[f32], cx: i32, cz: i32, gold_fill: f32, atlas: &Texture2D) -> (Option<Mesh>, Option<Mesh>, Option<Mesh>) {
+fn build_chunk(map: &Map, amb: &[f32], cx: i32, cz: i32, gold_fill: f32, atlas: &Texture2D, wall_sub: usize) -> (Option<Mesh>, Option<Mesh>, Option<Mesh>) {
     let mut mb = MB::new();
     let mut ov = MB::new();
     let mut ln = MB::new();
@@ -485,7 +486,7 @@ fn build_chunk(map: &Map, amb: &[f32], cx: i32, cz: i32, gold_fill: f32, atlas:
                 [dark; 4],
                 [Vec3::Y; 4],
             );
-            let n = WALL_SUB;
+            let n = wall_sub;
             let top_amb = amb_at(amb, xf + 0.5, zf + 0.5) * 0.95 + 0.1;
             build_grid(
                 &mut mb,
@@ -615,6 +616,8 @@ pub struct R3d {
     glow: Material,
     chunks: Vec<Chunk>,
     pub outlines: bool, // tile outlines on/off
+    wall_sub: usize,    // wall face subdivisions (detail)
+    pub max_lights: usize,
 }
 
 fn rgba(u: u32) -> Color {
@@ -645,7 +648,21 @@ fn chunk_sig(map: &Map, cx: i32, cz: i32, fill_bucket: u8) -> u64 {
 impl R3d {
     pub fn new() -> R3d {
         let chunks = (0..NCH * NCH).map(|_| Chunk { sig: 0, mesh: None, overlay: None, lines: None }).collect();
-        R3d { lit: lit_material(), glow: glow_material(), chunks, outlines: true }
+        R3d { lit: lit_material(), glow: glow_material(), chunks, outlines: true, wall_sub: 3, max_lights: MAX_LIGHTS }
+    }
+
+    // Changing the wall detail rebuilds all chunks
+    pub fn set_wall_detail(&mut self, sub: usize) {
+        if sub != self.wall_sub {
+            self.wall_sub = sub;
+            self.invalidate();
+        }
+    }
+
+    pub fn invalidate(&mut self) {
+        for c in self.chunks.iter_mut() {
+            c.sig = 0;
+        }
     }
 
     fn update_chunks(&mut self, g: &Game, gfx: &Gfx) {
@@ -658,7 +675,7 @@ impl R3d {
                 let ch = &mut self.chunks[(cz * NCH + cx) as usize];
                 if ch.sig != sig {
                     let a = amb.get_or_insert_with(|| ambient_field(&g.map));
-                    let (m, o, l) = build_chunk(&g.map, a, cx, cz, bucket as f32 / 6.0, &gfx.atlas);
+                    let (m, o, l) = build_chunk(&g.map, a, cx, cz, bucket as f32 / 6.0, &gfx.atlas, self.wall_sub);
                     ch.mesh = m;
                     ch.overlay = o;
                     ch.lines = l;
@@ -714,7 +731,7 @@ impl R3d {
             }
         }
         l.sort_by(|a, b| a.0.partial_cmp(&b.0).unwrap_or(std::cmp::Ordering::Equal));
-        l.truncate(MAX_LIGHTS);
+        l.truncate(self.max_lights.min(MAX_LIGHTS));
         let mut pos = vec![Vec4::ZERO; MAX_LIGHTS];
         let mut colr = vec![Vec4::ZERO; MAX_LIGHTS];
         for (k, (_, p, c)) in l.iter().enumerate() {