feat(linkedin-studio): honest newsletter distribution + profile-SEO + outreach pipeline

Step 17 (Wave 4 S4) of the audit remediation. Applies research/03 §D5 + the
two S2 residual fixes folded in. No new commands/agents (counts stay 27/19).

Newsletter (commands/newsletter.md): new "Distribution channel" section after
Step 10 teaching the HONEST native-newsletter mechanics — bypasses organic feed
ranking via ONE deduplicated notification per subscriber per edition (NOT a
three-touchpoint blast); the mass invite fires once → ~1-2K follower floor
(wait until you can spend it); realistic cold-start 0-100 subs months 1-3;
discloses non-export / no-canonical / no-read-analytics / per-subscriber decay;
explicit below-vs-above-floor decision rule. Sourced to research/03 D5.

Profile (commands/profile.md): new "Profile SEO" section — headline as the
highest-weight search field + a per-section keyword-target table
(headline/about/experience/skills/featured), consistency-over-stuffing rule.

Outreach (commands/outreach.md): Step 8c persists the pipeline board to tracked
state via the new recordOutreachContact mutation (mirrors Step 16's
recordFirstHourPlan): additive last_outreach_date/outreach_active scalars + a
non-R-initial ## Outreach Pipeline section in state-updater.mjs +
config/state-file.template.md + --record-outreach CLI branch. +7 tests
(state-updater 26→33, full hook suite 83→90).

Residual 1 (growth-playbook:216): 9:16 "distribution boost" → 4:5/1:1 guidance
(9:16 mobile-only opt-in; "immersive distribution" = uncorroborated heuristic).
Residual 2 (video-strategy-guide:300): "3-second test determines 70% retention"
→ "front-load value for muted autoplay" (three-second hook is folklore, not a
LinkedIn signal).

Verify: grep checks 1-5 pass; test-runner.sh exit 0 (stat-consistency green);
state-updater 33/33. [skip-docs] — tre-doc + version bump deferred to Step 21.

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

plugins/linkedin-studio/references/linkedin-growth-playbook-2025-2026.md

@@ -213,7 +213,7 @@ LinkedIn removed hashtag following, hashtag pages, and "Talks About" sections in
 **If using video:**
 - Optimal length: 60 seconds (2026 sweet spot — 30% completion rate minimum for any distribution)
 - Always add captions (85% watch with sound off)
-- Use vertical 9:16 format (1080x1920) for immersive feed distribution boost
+- **4:5 (1080×1350) or 1:1 (1080×1080) preferred** for broad feed distribution on a desktop-heavy professional audience; 9:16 is delivered mobile-only and crops to 1:1 on desktop — reserve it for the opt-in vertical video tab. No official 4:5-vs-9:16 engagement study exists, so treat the older "immersive distribution" framing as an uncorroborated heuristic, not a reach lever (see `references/linkedin-formats.md`).
 
 ### Text-Only Posts
 

plugins/linkedin-studio/references/video-strategy-guide.md

@@ -297,7 +297,7 @@ LinkedIn's algorithm weights **completion rate** above all other video metrics.
 - Use "open loops" — tease what's coming ("and the third one surprised me...")
 - Vary pacing to prevent monotony
 - Place visual changes every 5-7 seconds
-- Strong hook → the 3-second test determines 70% of retention
+- Front-load value for muted autoplay — ~85% watch without sound, so the opening must read and land with the audio off. (The "three-second hook" is cross-platform folklore, not a LinkedIn-named ranking signal; LinkedIn's only official "3 seconds" is the minimum video length. Open strong because attention is scarce, not because a fixed-second rule sets retention.)
 
 ### Vertical Video Preference