feat(phase-1): persistent generation library

- Save every completed generation to SQLite (generation_store.py) with
  WAV and waveform peaks written to data/generations/<id>/
- Deferred DB write until success — cancelled/errored generations never
  touch the DB and never appear in the library
- Fixed cancel+regenerate IndexError: _reset_scheduler_caches() now
  directly zeros scheduler._step_index and running state in addition to
  clearing VibePod cache dicts; same explicit resets added in the fresh
  path of prepare_noise_scheduler as belt-and-suspenders
- Added /library page with GenerationCard, WaveformPreview, waveform
  fetch, play/pause, download, delete, pagination, empty + error states
- Added generation API routes (list, single, audio stream, waveform,
  delete) proxying to Python server
- Added Library nav link to Header with active state
- Persist script/speaker/CFG to localStorage so generate page state
  survives navigation
- Updated build plan: Phase 0+1 ticked off, better-sqlite3 moved to
  Phase 2, architectural note on Python owning all persistence

web/app/api/generations/[id]/audio/route.ts

@@ -0,0 +1,23 @@
+import { NextRequest, NextResponse } from "next/server";
+
+export const dynamic = "force-dynamic";
+
+const pythonUrl = () => process.env.VIBEVOICE_SERVER_URL ?? "http://localhost:8000";
+
+export async function GET(_: NextRequest, { params }: { params: Promise<{ id: string }> }) {
+  const { id } = await params;
+  try {
+    const res = await fetch(`${pythonUrl()}/generations/${id}/audio`);
+    if (!res.ok) return NextResponse.json({ error: "Audio not found" }, { status: res.status });
+    return new NextResponse(res.body, {
+      status: 200,
+      headers: {
+        "Content-Type": "audio/wav",
+        "Content-Disposition": `attachment; filename="${id}.wav"`,
+        "Cache-Control": "public, max-age=31536000, immutable",
+      },
+    });
+  } catch {
+    return NextResponse.json({ error: "Failed to reach server" }, { status: 502 });
+  }
+}

web/app/api/generations/[id]/route.ts

@@ -0,0 +1,27 @@
+import { NextRequest, NextResponse } from "next/server";
+
+const pythonUrl = () => process.env.VIBEVOICE_SERVER_URL ?? "http://localhost:8000";
+
+export async function GET(_: NextRequest, { params }: { params: Promise<{ id: string }> }) {
+  const { id } = await params;
+  try {
+    const res = await fetch(`${pythonUrl()}/generations/${id}`, { cache: "no-store" });
+    if (!res.ok) return NextResponse.json({ error: "Not found" }, { status: res.status });
+    return NextResponse.json(await res.json());
+  } catch {
+    return NextResponse.json({ error: "Failed to reach server" }, { status: 502 });
+  }
+}
+
+export async function DELETE(_: NextRequest, { params }: { params: Promise<{ id: string }> }) {
+  const { id } = await params;
+  try {
+    const res = await fetch(`${pythonUrl()}/generations/${id}`, { method: "DELETE" });
+    if (res.status === 404)
+      return NextResponse.json({ error: "Not found" }, { status: 404 });
+    if (!res.ok) return NextResponse.json({ error: "Upstream error" }, { status: res.status });
+    return new NextResponse(null, { status: 204 });
+  } catch {
+    return NextResponse.json({ error: "Failed to reach server" }, { status: 502 });
+  }
+}

web/app/api/generations/[id]/waveform/route.ts

@@ -0,0 +1,16 @@
+import { NextRequest, NextResponse } from "next/server";
+
+const pythonUrl = () => process.env.VIBEVOICE_SERVER_URL ?? "http://localhost:8000";
+
+export async function GET(_: NextRequest, { params }: { params: Promise<{ id: string }> }) {
+  const { id } = await params;
+  try {
+    const res = await fetch(`${pythonUrl()}/generations/${id}/waveform`, { cache: "no-store" });
+    if (!res.ok) return NextResponse.json({ error: "Waveform not found" }, { status: res.status });
+    return NextResponse.json(await res.json(), {
+      headers: { "Cache-Control": "public, max-age=31536000, immutable" },
+    });
+  } catch {
+    return NextResponse.json({ error: "Failed to reach server" }, { status: 502 });
+  }
+}

web/app/api/generations/route.ts

@@ -0,0 +1,19 @@
+import { NextRequest, NextResponse } from "next/server";
+
+const pythonUrl = () => process.env.VIBEVOICE_SERVER_URL ?? "http://localhost:8000";
+
+export async function GET(request: NextRequest) {
+  const { searchParams } = new URL(request.url);
+  const limit = searchParams.get("limit") ?? "50";
+  const offset = searchParams.get("offset") ?? "0";
+
+  try {
+    const res = await fetch(`${pythonUrl()}/generations?limit=${limit}&offset=${offset}`, {
+      cache: "no-store",
+    });
+    if (!res.ok) return NextResponse.json({ error: "Upstream error" }, { status: res.status });
+    return NextResponse.json(await res.json());
+  } catch {
+    return NextResponse.json({ error: "Failed to reach server" }, { status: 502 });
+  }
+}