docs: record that CI, the registry and the deploy moved to Gitea

The pipeline change made a set of sentences false, and they are the only
record of why things are the way they are, so they move with it: the CI
section and deploy target in README, the cron and BASE_PATH notes in
ARCHITECTURE, the documented User-Agent in INGESTION, and the contact
URL in SOURCES.

Two comments in source were false in the same way and are fixed here
rather than left for the next reader. `serve.ts` said compression was
"the whole difference between the Docker image and the deployed site" —
the image *is* the deployed site now, so that negotiation is the only
compression any reader gets. `robots.ts` justified product-token
matching with "our contact URL contains the string StereotypicalCat",
which it no longer does; the hazard is the arbitrary substring, not that
one, so the comment now says so and the regression test keeps the URL
that actually caused it.

What is deliberately NOT rewritten: game8.co's refusal stays in the past
tense with the Gitea result marked unverified, in AGENTS.md, README,
SOURCES and FEEDBACK alike. A new runner address is the variable that
failure turns on, so it may well be served — but "may well be" is not
evidence, and the four places that would have to change are named
together so they change together once a cycle has actually run.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>

test/serve.test.ts

@@ -117,12 +117,13 @@ describe("static server", () => {
 });
 
 /**
- * Compression, which is the whole difference between the Docker image and the
- * deployed site.
+ * Compression, which used to be the whole difference between the Docker image
+ * and the deployed site.
  *
- * GitHub Pages gzips on our behalf, so the bundle crosses the wire at a third of
- * its size there and did not here — and this file is what the image runs. Three
- * times the bytes is the only thing a self-hoster would ever have seen.
+ * GitHub Pages gzipped on our behalf, so the bundle crossed the wire at a third
+ * of its size there and did not here — and serve.ts is what the image runs.
+ * Since the move to Gitea the image is the deploy, so these assertions cover
+ * every reader rather than only a self-hoster: nothing else compresses now.
  */
 describe("static server: compression", () => {
   test("gzips a text asset for a client that asks", async () => {