feat(web): add player name, freeform input, and unified settings modal

- Player name: stored in localStorage, injected into Architect/Writer/InsertBeat
  prompts so NPCs address the player by name, displayed in dialogue UI
- Freeform input: compact button at choice nodes expands to text input, LLM
  classifier routes to insert-beat (interactive NPC response) or change-scene
- SettingsModal: unified panel merging player name, voice toggle (with
  collapsible TTS key section), replacing the old TtsKeyModal
- Insert-beat upgrade: prompt now requires NPC reaction when characters are
  present, shared by both freeform and Vision paths
- IME guard: isComposing check on freeform input to prevent CJK mid-composition
  submission

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

lib/analytics.ts

@@ -49,6 +49,7 @@ type AnalyticsEventData = {
     kind: "advance-beat" | "change-scene";
   };
   vision_click: { result: "insert-beat" | "change-scene" };
+  freeform_input: { scene_index: number; text_length: number };
   tts_toggle: { muted: boolean };
   fullscreen_toggle: { on: boolean };
   play_heartbeat: never;