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>

hooks/scripts/posting-reminder.mjs

@@ -1,5 +1,5 @@
 #!/usr/bin/env node
-// Notification hook for linkedin-thought-leadership plugin
+// Notification hook for linkedin-studio plugin
 // Fires on idle_prompt to show posting reminders. Rate-limited: max once per 30 min.
 
 import { readFileSync, existsSync, statSync, writeFileSync, mkdirSync } from 'node:fs';
@@ -10,7 +10,7 @@ import { queueToday, queueOverdue } from './queue-manager.mjs';
 const __dirname = dirname(fileURLToPath(import.meta.url));
 const PLUGIN_ROOT = join(__dirname, '..', '..');
 const HOME = process.env.HOME || process.env.USERPROFILE || '';
-const STATE_FILE = join(HOME, '.claude', 'linkedin-thought-leadership.local.md');
+const STATE_FILE = join(HOME, '.claude', 'linkedin-studio.local.md');
 const SESSION_DIR = '/tmp/linkedin-hooks';
 const COOLDOWN_FILE = join(SESSION_DIR, 'last-notification');
 const COOLDOWN_SECONDS = 1800;