0.3.1

## New Web APIs
- **File API** (`File`/`FileList` implementation)
- `import.meta.resolve`
- Custom element reactions v2; `parseHtmlAsChildren` handling for unexpected DOM in custom-element callbacks
- WebSocket now works in workers; Performance API on workers; worker-safe `Event`
- Forms: `enctype` + 5 submitter `form-*` IDL accessors
- `Navigator.appCodeName` returns `Mozilla`

## CSS / styling
- Evaluate `@media` and `matchMedia` against viewport
- `--enable-external-stylesheets` flag (fetch + parse)
- Author `display` rule beats UA `[hidden]` / `display:none`
- Surface at-rules through `insertRule` and `replaceSync`

## CDP (Chrome DevTools Protocol)
- **webMCP API + webMCP CDP domain**
- `Accessibility.queryAXTree` (+ latent frame-binding bug fix); WebDriver `getComputedLabel`
- Cache: `Network.requestServedFromCache`, `fromDiskCache` field on `Network.Response`, `Network.clearBrowserCache` / `canClearBrowserCache`, proper `Network.setCacheDisabled`
- Accessibility: use content for name on specific roles
- Re-organized CDP connection; Main/Network reads CDP socket

## HTTP / Networking
- Send `Accept` header when navigating
- Cache eviction; serve cache from next client tick
- `fetch` uses httpClient (respects `Config.maxConnections`)
- `--json` flag for the `fetch` command

## Security / correctness
- `URL`: fix NUL/CR/LF/TAB character injection through authority
- `Cookie`: honor `SameSite=Strict` on cross-site navigation; cleaner `validateCookieString`
- Correct scheme parsing with leading whitespace
- Emit `null` when JSON-stringifying unserializable values

## Stability fixes
- **Fix CDP server stall / SIGTERM hang in optimized builds** (Network drops CDP sockets from poll set); terminate live CDP connections on shutdown
- Protect against recursive form submits; dangling pointer in `syncRequest`
- Scope frame ID generator to Browser, not Session (#2472)
- Move `FinalizerCallbackIdentity` lifetime from Session to Browser
- Replace active page on synthetic root navigation (about:blank, blob:); ensure about:blank frame visibility
- Dump using latest Frame to prevent segfault on frame change
- Clear pending destroy on `createPage`; don't process scripts that failed to load

## Performance
- `Timers`: integer-optimized hashing
- HttpClient/Transfer cleanup

## Build / CI / dev
- `make download-v8` to fetch prebuilt V8 and skip source build; forward optional `V8_PATH`; `make clean` target
- Reworked `help` command; removed options from main help
- Smoke-test the MCP stdio server; remove CDP logs from e2e tests; force-kill lightpanda between steps
- Dockerfile: fix `curl|sh` pipefail, trim builder stage