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/engine/orchestrator.ts

@@ -2,6 +2,9 @@ import type {
   BeatAudioRequest,
   BeatAudioResponse,
   EngineConfig,
+  FreeformClassify,
+  FreeformClassifyRequest,
+  FreeformClassifyResponse,
   InsertBeatRequest,
   InsertBeatResponse,
   Session,
@@ -13,10 +16,16 @@ import type {
   VisionResponse,
 } from "@infiplot/types";
 import { coerceOrientation } from "@infiplot/types";
+import { chat } from "@infiplot/ai-client";
 import { runArchitect } from "./agents/architect";
 import { selectStyle } from "./agents/styleSelector";
 import { directInsertBeat, directScene } from "./director";
 import { STYLE_MAP } from "@/lib/options";
+import { parseJsonLoose } from "./jsonParser";
+import {
+  FREEFORM_CLASSIFY_SYSTEM,
+  buildFreeformClassifyUserMessage,
+} from "./prompts";
 import { synthesizeBeat } from "./voice";
 import { interpret } from "./vision";
 
@@ -52,6 +61,7 @@ export async function startSession(
     characters: [],
     styleReferenceImage: req.styleReferenceImage?.trim() || undefined,
     orientation: coerceOrientation(req.orientation),
+    playerName: req.playerName?.trim() || undefined,
   };
 
   // Stage 0 — Architect (+ optional auto style selection, in parallel).
@@ -138,6 +148,41 @@ export async function visionDecide(
   return interpret(config.vision, req.annotatedImageBase64, current);
 }
 
+// ──────────────────────────────────────────────────────────────────────
+//  classifyFreeform — classifies a freeform text input at a choice node
+//  into match-choice / insert-beat / change-scene. Single lightweight
+//  LLM call; no image, no scene generation.
+// ──────────────────────────────────────────────────────────────────────
+
+export async function classifyFreeform(
+  config: EngineConfig,
+  req: FreeformClassifyRequest,
+): Promise<FreeformClassifyResponse> {
+  const current = req.session.history.at(-1)?.scene ?? null;
+  const userMsg = buildFreeformClassifyUserMessage(
+    req.freeformText,
+    current?.scenePrompt,
+  );
+
+  const raw = await chat(config.text, [
+    { role: "system", content: FREEFORM_CLASSIFY_SYSTEM },
+    { role: "user", content: userMsg },
+  ], { temperature: 0, tag: "freeform-classify" });
+
+  const parsed = parseJsonLoose<{
+    classify?: string;
+    freeformAction?: string;
+  }>(raw);
+
+  const classify: FreeformClassify =
+    parsed.classify === "change-scene" ? "change-scene" : "insert-beat";
+
+  return {
+    classify,
+    freeformAction: parsed.freeformAction?.trim() || req.freeformText,
+  };
+}
+
 // ──────────────────────────────────────────────────────────────────────
 //  requestInsertBeat — single-agent transient beat (no image, no new
 //  characters). Stays single-LLM by design — the INSERT_BEAT prompt