refactor(linkedin)!: rename plugin linkedin-thought-leadership → linkedin-studio (v3.0.0)

BREAKING CHANGE: the marketplace slug, the agent namespace
(linkedin-studio:<agent>), and the runtime state-file path
(~/.claude/linkedin-studio.local.md) all change. Reinstall required;
existing state migrated in place (post metrics, streak, history preserved).
The /linkedin:* commands are unchanged — the command namespace is set
per-command in frontmatter and was always independent of the plugin slug.
Functionality is byte-identical to v2.4.0; this release is pure identity.

- dir + manifests: plugins/linkedin-studio + plugin.json + root marketplace.json
- agent namespace updated in commands/newsletter.md (only functional invoker)
- state path updated in 4 hook scripts + topic-rotation prompt + state template
- catch-all skill dir renamed skills/linkedin-studio (5 functional skills unchanged)
- docs + version bump to 3.0.0 across README badge, CHANGELOG, root README/CLAUDE.md
- historical records (CHANGELOG past entries, docs/ build artifacts,
  config-audit v5.0.0 snapshots) intentionally retain the old slug

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

plugins/linkedin-studio/.gitignore

@@ -0,0 +1,51 @@
+# Secrets and sensitive files
+.mcp.json
+.env
+.env.*
+
+# Local configuration
+*.local.md
+
+# Session state (personal activity, auto-initialized from template)
+REMEMBER.md
+
+# Credentials
+credentials.json
+*-secret*
+*.pem
+*.key
+
+# OS files
+.DS_Store
+Thumbs.db
+
+# IDE
+.idea/
+.vscode/
+*.swp
+*.swo
+
+# Temporary files
+*.tmp
+*.bak
+
+# Draft content (personal posts)
+assets/drafts/queue.json
+assets/drafts/week-*/
+
+# Analytics data (personal performance data)
+assets/analytics/exports/
+assets/analytics/posts/
+assets/analytics/weekly-reports/
+assets/analytics/content-history.md
+
+# Internal development files (not for public release)
+BACKLOG.md
+docs/DEVELOPMENT-LOG.md
+
+# Generated annotation/review artifacts (regenerable; annotations live in browser localStorage)
+docs/review/
+
+# Node.js
+scripts/analytics/node_modules/
+scripts/analytics/build/