docs(lint): correct the Vale scalar, size-ceiling and release-gate claims

Four claims in shipped agent-facing docs did not match verified behaviour.
These are read as ground truth by agents in other repos, so each was
reproduced against vale 3.15.2 before rewriting:

- CONTEXT.md and `vale-config/SKILL.md` said both `>` and `|` block scalars
  break the description scope. `|` does not — it lints normally and fires every
  alert, while `>` yields zero. An agent following the old text would rewrite a
  working `|` description into a plain multi-line scalar, which genuinely does
  break, inverting the intended remediation. Both now name the forms that do
  break and state that `|` does not.
- CONTEXT.md and ADR-0013 described the size hook as failing only above 500
  lines, omitting the 2900-word gate it also enforces. Both now describe the
  pair and state that `validate.sh` checks the same two.
- ADR-0014 recorded an accepted residual — a wholesale `assets/` deletion going
  unflagged — that commit 14c2c91 closed. Left as the point-in-time record and
  amended with an update describing the union-with-tag-manifest mechanism,
  following the amendment precedent in ADR-0005.
- `vale-config/SKILL.md` asserted a fresh `.vale.ini` fails until `vale sync`
  runs, contradicting its own note that built-in styles need no download. The
  claim is now scoped to package styles; this repo's two configs declare no
  packages and lint clean with zero syncs.

Also repoints AGENTS.md at the seven `gitea:*` skills — the `bin:gitea` route
it named no longer exists.

Refs: #85

docs/adr/0013-vale-harness-scope-and-rule-sources.md

@@ -95,8 +95,13 @@ every rule to `level: error` is what actually implements this decision.
   catch does not pay for a permanent suppression, so the rule is deleted and this ADR's
   "cherry-picked rules" is one rule, not two.
 - A new pre-commit hook, `skill-size-check` (`scripts/skill-size-check.sh`), enforces the
-  500-line/5,000-token `SKILL.md` ceiling, sibling to `skill-frontmatter`. It fails only *above*
-  500 lines, matching `skill-audit/scripts/validate.sh`'s long-standing `<= 500` pass.
+  500-line/5,000-token `SKILL.md` ceiling, sibling to `skill-frontmatter`. Both halves of that
+  ceiling are blocking gates, not just the line count: `MAX_LINES=500`, and `MAX_WORDS=2900` as a
+  word-count proxy for the 5,000-token limit (calibrated from this repo's measured ~1.6-1.7 tokens
+  per word — `wc -w` is not BPE tokenization). Either one exceeded fails the hook. Both are
+  inclusive: a file at exactly 500 lines or exactly 2,900 words passes, and only one past a ceiling
+  fails. `skill-audit/scripts/validate.sh` enforces the same pair on the same inclusive terms, so
+  the audit and the commit hook cannot disagree about whether a given `SKILL.md` is over size.
 - `styles/KyberforgeTrial/` and `.vale.trial.ini` were deliberately not created — noted here so a
   future reader doesn't wonder if a trial tier was forgotten.
 - The styles-portability question — whether `styles/` and `.vale.ini` should move into