f1-stream: add chrome-browser, subreddit, dd12 extractors; fix streamed.pk

User asked to broaden the source pipeline so f1-stream can find F1 (and
adjacent motorsport) streams from Sky Sports / DAZN / Reddit / etc.,
using the in-cluster chrome-service headed browser where needed. Four
changes:

1. **streamed.py**: BASE_URL streamed.su → streamed.pk. The .su domain
   stopped serving the API host in 2026 (only the marketing page is
   left); .pk hosts the JSON API now. Adds 3 events/round (currently
   all routed through embedsports.top — see #2 caveat).

2. **chrome_browser.py** (new): generic chrome-service-driven extractor.
   Connects to the existing chrome-service WS (CHROME_WS_URL +
   CHROME_WS_TOKEN env), navigates a list of TARGETS, captures any HLS
   playlist URL the page fetches at runtime, returns one ExtractedStream
   per discovery. Uses the same stealth init script as the verifier so
   anti-bot checks don't trip the page. Handles iframes (DD12-style
   /nas → /new-nas/jwplayer) and probes child-frame <video>/source
   elements after settle. Caveat: most aggregator sites (pooembed,
   embedsports, hmembeds, even DD12's JW Player path) use a broken
   runtime decoder that produces no m3u8 in our environment, so the
   TARGETS list is currently 0-yielding; the framework is the
   contribution and concrete sites can be added as they're discovered.

3. **subreddit.py** (new): scans r/MotorsportsReplays, r/motorsports,
   r/formula1, r/motogp via the public old.reddit.com JSON API for
   posts whose flair/title indicates a live stream. Discovered URLs
   are returned as embed-type streams; the verifier visits each via
   chrome-service to confirm playability. Note: Reddit currently HTTP
   403's our cluster outbound IP for anonymous JSON requests; the
   extractor returns 0 in that state and logs a debug message. Will
   work from any IP Reddit isn't blocking.

4. **dd12.py** (new): inline-HTML scraper for DD12Streams. The site
   embeds `playerInstance.setup({file: "..."})` directly in HTML — no
   JS decoder needed. Currently surfaces NASCAR Cup Series 24/7 (clean
   BunnyCDN-hosted HLS at w9329432hnf3h34.b-cdn.net/pdfs/master.m3u8);
   add new `(path, label, title)` tuples to CHANNELS as DD12 expands.

Result: /streams now shows 2 verified live streams (Rally TV via
pitsport + DD12 NASCAR Cup 24/7). When the next F1 weekend (Canadian
GP, May 22-24) goes live, pitsport will surface F1 sessions
automatically via the existing pushembdz path.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

stacks/f1-stream/files/backend/extractors/streamed.py

@@ -9,7 +9,9 @@ from backend.extractors.models import ExtractedStream
 
 logger = logging.getLogger(__name__)
 
-BASE_URL = "https://streamed.su"
+# Site renamed from streamed.su → streamed.pk in 2026; the .su domain
+# stopped resolving the API host (only the marketing page is left).
+BASE_URL = "https://streamed.pk"
 USER_AGENT = (
     "Mozilla/5.0 (Windows NT 10.0; Win64; x64) "
     "AppleWebKit/537.36 (KHTML, like Gecko) "