fix(kyberforge): align the audit word ceiling and drop the fragile --config

Three divergences between what the audit skills claim and what the hooks
enforce, each of which fails silently rather than loudly:

- `skill-size-check.sh` blocked at 2900 words while `validate.sh` checked only
  the 500-line ceiling, so `/skill-audit` could report a skill ready to ship
  that the commit hook then rejected. `validate.sh` now checks the same pair on
  the same inclusive terms; the constants are duplicated with a comment naming
  the other file, because a plugin skill's scripts cannot read outside the
  plugin directory once installed to the cache.
- Both audit skills' Step 1 passed `--config assets/vale/.vale.ini`, which is
  redundant (the wrapper self-locates its sibling config) and fragile: an agent
  that resolves the script path against the skill directory but not the config
  path gets E100, exit 2, which the surrounding fallback clause misreads as
  "vale unavailable" and downgrades to full LLM judgment with no signal.
- The external-consumer test registered only the two Vale hooks, never the
  third shipped hook, so a lost executable bit would have broken every consumer
  while the local suite stayed green. Verified by mutation: `chmod 644` on the
  copied script now turns three passes into two failures.

Also corrects the size hook's calibration comment, which claimed ~5.7-6.5
characters per word against a corpus whose measured median is 6.79 — the stated
upper bound sat below the median, so the "calibrated with margin" claim was
inverted for prose-dense files. MAX_WORDS is unchanged pending a decision; the
comment is now explicit that the gate holds under 5,000 tokens for typical
prose density, not for any file.

Refs: #85

tests/test-skill-size-check.sh

@@ -1,6 +1,8 @@
 #!/usr/bin/env bash
 # Regression test for scripts/skill-size-check.sh: enforces agentskills.io's
-# 500-line/5,000-word(proxy-for-token) SKILL.md size ceiling.
+# 500-line/5,000-token SKILL.md size ceiling. The token half is enforced via a
+# word-count proxy (MAX_WORDS, currently 2900) — 5,000 is the token ceiling,
+# 2,900 is the word budget the script derives from it.
 set -euo pipefail
 
 REPO_ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
@@ -55,9 +57,9 @@ echo ""
 echo "--- fails a file over the word-count limit ---"
 MANY_WORDS="$(make_fixture many-words 10 600)"
 if "$SCRIPT" "$MANY_WORDS" 2>/dev/null; then
-  fail "file over the 5,000-word ceiling should have exited non-zero"
+  fail "file over the word ceiling should have exited non-zero"
 else
-  pass "file over the 5,000-word ceiling exits non-zero"
+  pass "file over the word ceiling exits non-zero"
 fi
 
 # Boundary-pair tests below read the script's current MAX_WORDS rather than