Add opt-in ambient music control (task o8)

- Change ambient playback hotkey from 'm' to 'p'
- Move flash effect hotkey from 'p' to 'f'
- Update nav button labels: '<kbd>p</kbd> music' and '<kbd>f</kbd> flash'
- Update splash hint to advertise 'p' music alongside 'w' wild
- Add 'p' and 'f' hotkey support in splash and modal states
- Persist ambient enabled/disabled state in localStorage (snonuxAmbientEnabled)
- Default off; restore preference on page load without overwriting via wild mode
- Improve accessibility with explicit aria-labels and aria-pressed state sync

2 files changed, 33 insertions, 6 deletions

diff --git a/internal/generator/templates/shared/nav.tmpl b/internal/generator/templates/shared/nav.tmpl
index b22ae0a..4f620a5 100644
--- a/internal/generator/templates/shared/nav.tmpl
+++ b/internal/generator/templates/shared/nav.tmpl
@@ -58,8 +58,8 @@
         <button type="button" class="nav-fx-button" data-sno-fx="wild" aria-pressed="false" aria-label="Toggle wild mode"><kbd>w</kbd> wild</button>
         <button type="button" class="nav-fx-button" data-sno-fx="crt" aria-pressed="false" aria-label="Toggle CRT effect"><kbd>c</kbd> crt</button>
         <button type="button" class="nav-fx-button" data-sno-fx="ghost" aria-pressed="false" aria-label="Toggle ghost mode"><kbd>g</kbd> ghost</button>
-        <button type="button" class="nav-fx-button" data-sno-fx="ambient" aria-pressed="false" aria-label="Toggle ambient sound"><kbd>m</kbd> ambient</button>
-        <button type="button" class="nav-fx-button" data-sno-fx="flash" aria-label="Trigger flash effect"><kbd>p</kbd> flash</button>
+        <button type="button" class="nav-fx-button" data-sno-fx="ambient" aria-pressed="false" aria-label="Start or pause ambient music"><kbd>p</kbd> music</button>
+        <button type="button" class="nav-fx-button" data-sno-fx="flash" aria-label="Trigger flash effect"><kbd>f</kbd> flash</button>
         <button type="button" class="nav-fx-button" data-sno-fx="scatter" aria-label="Trigger scatter effect"><kbd>x</kbd> scatter</button>
         <span class="nav-hints-spacer"><kbd>t</kbd> theme</span>
         <select id="sno-theme-select" class="nav-fx-button" aria-label="Theme"></select>
diff --git a/internal/generator/templates/shared/shared.js b/internal/generator/templates/shared/shared.js
index 31c19ed..eb7e8e5 100644
--- a/internal/generator/templates/shared/shared.js
+++ b/internal/generator/templates/shared/shared.js
@@ -1242,10 +1242,18 @@
         syncFxButtonStates();
     }
 
+    function snonuxAmbientSavePreference(enabled) {
+        try { localStorage.setItem('snonuxAmbientEnabled', enabled ? '1' : '0'); } catch (_) {}
+    }
+    function snonuxAmbientLoadPreference() {
+        try { return localStorage.getItem('snonuxAmbientEnabled') === '1'; } catch (_) { return false; }
+    }
+
     function toggleAmbientMode() {
         if (window.snonuxAmbientToggle) window.snonuxAmbientToggle();
         pulseFxButton('ambient');
         syncFxButtonStates();
+        snonuxAmbientSavePreference(window.snonuxAmbientIsPlaying && window.snonuxAmbientIsPlaying());
     }
 
     function triggerFlashEffect() {
@@ -1277,13 +1285,21 @@
         syncFxButtonStates();
     })();
 
+    // Restore ambient preference on load (opt-in; default off).
+    (function initAmbientPreference() {
+        if (snonuxAmbientLoadPreference() && window.snonuxAmbientStart) {
+            window.snonuxAmbientStart('restore');
+        }
+        syncFxButtonStates();
+    })();
+
     // Inject keyboard controls hint into splash overlay (all themes)
     (function enhanceSplashHint() {
         var hint = document.querySelector('#splash-overlay .splash-hint');
         if (!hint || document.querySelector('#splash-overlay .splash-controls')) return;
         var extra = document.createElement('div');
         extra.className = 'splash-controls';
-        extra.innerHTML = '<kbd>↑</kbd><kbd>↓</kbd><kbd>←</kbd><kbd>→</kbd> drift \u2022 <kbd>w</kbd> wild \u2022 <kbd>m</kbd> ambient \u2022 <kbd>Enter</kbd> open';
+        extra.innerHTML = '<kbd>↑</kbd><kbd>↓</kbd><kbd>←</kbd><kbd>→</kbd> drift \u2022 <kbd>w</kbd> wild \u2022 <kbd>p</kbd> music \u2022 <kbd>Enter</kbd> open';
         hint.appendChild(extra);
     })();
 
@@ -1350,9 +1366,12 @@
             } else if (e.key === 'w' && !e.repeat) {
                 e.preventDefault();
                 toggleWildMode({ splashMode: true, kickSplash: true });
-            } else if (e.key === 'm' && !e.repeat) {
+            } else if (e.key === 'p' && !e.repeat) {
                 e.preventDefault();
                 toggleAmbientMode();
+            } else if (e.key === 'f' && !e.repeat) {
+                e.preventDefault();
+                triggerFlashEffect();
             } else if (e.key === 'c' && !e.repeat) {
                 e.preventDefault();
                 toggleCrtMode();
@@ -1370,6 +1389,14 @@
         }
         if (document.getElementById('post-modal').classList.contains('active')) {
             if (e.key === 'Escape') { closeModal(); e.preventDefault(); }
+            else if (e.key === 'p' && !e.repeat) {
+                e.preventDefault();
+                toggleAmbientMode();
+            }
+            else if (e.key === 'f' && !e.repeat) {
+                e.preventDefault();
+                triggerFlashEffect();
+            }
             else if (e.key === 't' && !e.repeat) {
                 e.preventDefault();
                 var pick = snonuxRandomTheme();
@@ -1416,7 +1443,7 @@
                 toggleWildMode();
                 e.preventDefault(); break;
             }
-            case 'm': {
+            case 'p': {
                 toggleAmbientMode();
                 e.preventDefault(); break;
             }
@@ -1426,7 +1453,7 @@
             case 'g':
                 toggleGhostMode();
                 e.preventDefault(); break;
-            case 'p':
+            case 'f':
                 triggerFlashEffect();
                 e.preventDefault(); break;
             case 'x':