initial code (#2)

* feat: initial code port from hyperframes-internal

Port all OSS-ready packages from the internal monorepo:
- @hyperframes/core — shared types, HTML generation, GSAP utilities, runtime
- @hyperframes/cli — CLI for creating, previewing, and rendering compositions
- @hyperframes/engine — framework-agnostic rendering engine (BeginFrame + FFmpeg)
- @hyperframes/producer — video rendering pipeline (Puppeteer + FFmpeg)
- @hyperframes/ui-player — browser-based video player component
- @hyperframes/studio — composition editor (React frontend + Hono backend)

Includes regression test suite with Docker-based test harness.

All HeyGen-internal references, deployment infrastructure, and
proprietary assets have been removed. Package names migrated
from @app/* to @hyperframes/*.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: scrub internal codenames and stale references from OSS port

- Replace static.heygen.ai runtime URLs in test fixtures
- Remove internal CDN publish script (publish-hyperframe-runtime.ts)
- Replace sandbox-studio, sandbox-interceptor, __magicEditRuntime
  with neutral names (studio, hyperframe-runtime, __hyperframeRuntime)
- Fix stale Vault API / localhost references in docs
- Remove broken deprecated_studio link

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: remove remaining internal codenames and stale references

- Delete stale producer README.md and PIPELINE.md (referenced nonexistent files)
- Replace "Cerberus" codename with "HyperFrames" in test design reviews
- Replace magic-edit postMessage identifiers with hf-preview/hf-parent
- Rename debug-magic-edit-timeline.ts to debug-timeline.ts
- Replace "Motion Cut" with "HyperFrames" in Timeline comments
- Fix studio/CLI references to nonexistent archive package
  (use local data/projects/ dir, stub render proxy)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/engine/src/config.test.ts

@@ -0,0 +1,95 @@
+import { describe, it, expect, beforeEach, afterEach } from "vitest";
+import { resolveConfig, DEFAULT_CONFIG } from "./config.js";
+
+describe("resolveConfig", () => {
+  const savedEnv = new Map<string, string | undefined>();
+
+  function setEnv(key: string, value: string) {
+    savedEnv.set(key, process.env[key]);
+    process.env[key] = value;
+  }
+
+  beforeEach(() => {
+    savedEnv.clear();
+  });
+
+  afterEach(() => {
+    for (const [key, value] of savedEnv) {
+      if (value === undefined) {
+        delete process.env[key];
+      } else {
+        process.env[key] = value;
+      }
+    }
+  });
+
+  it("returns defaults when no overrides or env vars are set", () => {
+    const config = resolveConfig();
+    expect(config.fps).toBe(30);
+    expect(config.quality).toBe("standard");
+    expect(config.format).toBe("jpeg");
+    expect(config.jpegQuality).toBe(80);
+    expect(config.debug).toBe(false);
+  });
+
+  it("applies explicit overrides over defaults", () => {
+    const config = resolveConfig({ fps: 60, debug: true });
+    expect(config.fps).toBe(60);
+    expect(config.debug).toBe(true);
+    // Non-overridden fields remain at defaults
+    expect(config.quality).toBe("standard");
+  });
+
+  it("reads numeric env vars with PRODUCER_ prefix", () => {
+    setEnv("PRODUCER_MAX_WORKERS", "4");
+    setEnv("PRODUCER_CORES_PER_WORKER", "3");
+
+    const config = resolveConfig();
+    expect(config.concurrency).toBe(4);
+    expect(config.coresPerWorker).toBe(3);
+  });
+
+  it("reads boolean env vars (true/false strings)", () => {
+    setEnv("PRODUCER_DISABLE_GPU", "true");
+    setEnv("PRODUCER_ENABLE_BROWSER_POOL", "true");
+
+    const config = resolveConfig();
+    expect(config.disableGpu).toBe(true);
+    expect(config.enableBrowserPool).toBe(true);
+  });
+
+  it("treats non-'true' boolean env vars as false", () => {
+    setEnv("PRODUCER_DISABLE_GPU", "yes");
+
+    const config = resolveConfig();
+    expect(config.disableGpu).toBe(false);
+  });
+
+  it("explicit overrides take precedence over env vars", () => {
+    setEnv("PRODUCER_CORES_PER_WORKER", "5");
+
+    const config = resolveConfig({ coresPerWorker: 8 });
+    expect(config.coresPerWorker).toBe(8);
+  });
+
+  it("falls back to defaults for invalid numeric env vars", () => {
+    setEnv("PRODUCER_CORES_PER_WORKER", "not-a-number");
+
+    const config = resolveConfig();
+    expect(config.coresPerWorker).toBe(DEFAULT_CONFIG.coresPerWorker);
+  });
+
+  it("clamps chunkSizeFrames to minimum of 120", () => {
+    setEnv("PRODUCER_CHUNK_SIZE_FRAMES", "50");
+
+    const config = resolveConfig();
+    expect(config.chunkSizeFrames).toBe(120);
+  });
+
+  it("clamps frameDataUriCacheLimit to minimum of 32", () => {
+    setEnv("PRODUCER_FRAME_DATA_URI_CACHE_LIMIT", "10");
+
+    const config = resolveConfig();
+    expect(config.frameDataUriCacheLimit).toBe(32);
+  });
+});