feat(lint): expand Vale audit prefilter into a broader plugin-content harness

Deferred item from PR #85 review. Per ADR-0013: cherry-picks two low-noise
rules from trialing write-good/alex against the real corpus (VagueQualifier,
SentenceOpenerThereIs) into styles/Kyberforge rather than adopting either
package wholesale (both are tuned for blog prose and were noisy on this
repo's terse, imperative instruction files - see the ADR's rejected-rule
list). Adds a new skill-size-check pre-commit hook enforcing agentskills.io's
500-line/5,000-token SKILL.md ceiling, currently unenforced. Fixes the 28
resulting violations across 20 existing SKILL.md/agent files so the
enforcing pre-commit hook lands clean.

governance.md/CONTROLS.md were evaluated and excluded as rule sources -
they're org/CI-infrastructure controls, not prose patterns Vale can express.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QUDczvw1H3eEeMD29Q9Lbi

plugins/kyberforge/skills/skill-author/SKILL.md

@@ -114,7 +114,7 @@ Rename the placeholder section heading to one that fits the skill's structure
 Ask of every sentence: "Would the agent get this wrong without it?" Cut anything that answers "no."
 
 **Include:**
-- Non-obvious sequences or ordering constraints — the agent may skip or reorder steps without this
+- Sequences or ordering constraints that aren't self-evident — the agent may skip or reorder steps without this
 - Domain conventions the agent cannot infer from general knowledge — this is the core value a skill adds
 - One default per decision point, plus one escape hatch — never a menu; menus cause the agent to pause or pick arbitrarily
 - Gotchas — facts that defy reasonable assumptions; the agent will get these wrong every time without them