fix(linkedin-studio): S1 hardening — method calibration (quick) + Start journey

Hardening phase S1. Tightened the hook character bound from one-sided
(under 140) to the full canonical 110-140 band across the Start-journey
creation surfaces, matching hooks/prompts/content-quality-gate.md:
- quick.md: hook band on Step 2 + Step 5 checklist; added a buzzword check
  and a 150-500 length-band check; checklist tally 6 -> 7.
- onboarding.md: hook band in Phase 3.2 + 3.3 (length + no-links already present).
- first-post.md: hook band in Step 4 + Step 5 (length + no-links already present).
- setup.md: zero-edit pass (all four axes already satisfied).

Adds docs/hardening/log.md (per-command audit trail, 5-step method) and
docs/hardening/review.md (cold /trekreview: ALLOW, 0 BLOCKER/0 MAJOR/1 MINOR).
Lint Failed:0, counts 29/19/25/6 unchanged. No structural/version churn.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

plugins/linkedin-studio/commands/onboarding.md

@@ -197,7 +197,7 @@ Then ask: "Give me a sentence or two about what you have in mind." If expertise
 ### 3.2 — Write the post (3-line formula)
 
 Draft the post using the voice profile from Phase 2 (or the existing `assets/voice-samples/` profile):
-- **Line 1 — Hook (under 140 chars):** specific to their experience, no generic opening
+- **Line 1 — Hook (110-140 chars):** specific to their experience, no generic opening
 - **Line 2 — Context (1-3 sentences):** the what and why, kept tight
 - **Line 3 — Insight + question:** their takeaway, ending on a genuine question that invites comments
 
@@ -206,7 +206,7 @@ Target 150-500 characters (short posts perform well for new accounts). One point
 ### 3.3 — Quick quality check
 
 Confirm 4 things before presenting:
-- [ ] Hook works in 140 chars?
+- [ ] Hook in the 110-140 band (not just under 140)?
 - [ ] ONE clear point (not three)?
 - [ ] Ends with a question or invitation?
 - [ ] Sounds like THEM (not corporate/AI)?