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/SECURITY.md

@@ -0,0 +1,28 @@
+# Security Policy
+
+## Reporting a Vulnerability
+
+If you discover a security vulnerability in this plugin, please report it responsibly.
+
+**Do NOT open a public issue for security vulnerabilities.**
+
+Instead, please email the maintainer directly or use GitHub's private vulnerability reporting feature.
+
+## Security Considerations
+
+This plugin:
+
+- Does not store credentials or API keys
+- Does not make external network requests (except when using WebFetch for URL processing)
+- Does not execute arbitrary code
+- Stores all data locally in markdown files
+
+## User Data
+
+- The `config/user-profile.local.md` file contains personal preferences
+- This file is gitignored by default to prevent accidental commits
+- Review your `.gitignore` before pushing to ensure no personal data is committed
+
+## Dependencies
+
+This plugin has no external dependencies beyond Claude Code itself.