chore(facts): protocol 5 and Module API 1.9.0 -- HOLD until the cutover

Engagement Phase 12b. **This branch is deliberately red and must not be merged until the
Phase 13 cutover has landed link and servuo-plugins on `main` and CI has republished the
bundle.** checkFacts.mjs fetches every value from the source repo's `main`, so it fails
today exactly as designed:

  FAIL  protocol (sidecar)   platform.json 5   link main 4
  FAIL  protocol (overlay)   platform.json 5   servuo-plugins main 4
  FAIL  moduleApi            platform.json 1.9.0   website main 1.6.0
  FAIL  protocol (bundle)    platform.json 5   installer bundles:current.json 4

Every other check is green on this branch: checkLinks 2503, checkReference 22, checkA11y,
checkCsp, checkSidebar, 42 tests.

moduleApi is **1.9.0**, not the 1.7.0 the plan named -- Phase 11 moved it twice after that
sentence was written (1.8.0 for the `admin` ceiling, 1.9.0 for the module seed API).

## Also: the one page whose whole subject is the protocol number was the one page that
## hardcoded it

platform.json's own header says no version number is ever hardcoded in prose, and
`architecture/protocol-versions.mdx` had `4` written out three times -- the headline
sentence and both declaration-site rows. It now imports platform.json like every other
page that quotes a fact, so it moves with the JSON and cannot say 4 while the JSON says 5.

Note the interpolation is OUTSIDE the code spans: MDX does not evaluate an expression
inside backticks, so `PROTOCOL_VERSION: u32 = {platform.protocol}` would have rendered the
braces literally. Verified in the built HTML -- "currently 5", and no `platform.protocol`
survives anywhere in the output.

The same page's "what a bump obliges" section said version 4 was the first bump to need a
store migration, which read as though every bump does. v5 needed none (it only widens
frames the store already keeps whole -- docs link/v5.md), so the sentence now says which
did and which did not, and v5.md joins v4.md under canonical documents.

## The fill-in step, at merge time

Three values are not knowable today because the artefact does not exist yet. After the
bundle republishes, run:

    GITEA_TOKEN=<token> node scripts/checkFacts.mjs

and copy what it prints in the "says" column into src/data/platform.json:

  * bundle.tag, bundle.sidecar, bundle.overlay -- from installer bundles:current.json
  * releases.Module-uo -- if the cutover cuts a new module release
  * verifiedOn -- the date you ran it

Then re-read `getting-started/connect-a-game-server` and `administration/the-shard-connection`,
which quote the bundle, before merging. The check is green when all 19 agree.

AI-assisted: written with Claude Code.

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

src/data/platform.json

@@ -14,9 +14,9 @@
 
   "verifiedOn": "2026-08-19",
 
-  "protocol": 4,
+  "protocol": 5,
 
-  "moduleApi": "1.6.0",
+  "moduleApi": "1.9.0",
 
   "bundle": {
     "tag": "2026.08.19",