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/ical-generator.mjs

@@ -1,5 +1,5 @@
 #!/usr/bin/env node
-// RFC 5545 iCal generator for linkedin-thought-leadership plugin
+// RFC 5545 iCal generator for linkedin-studio plugin
 // Import: import { generateIcal, generateIcalFromQueue, writeIcalFile } from './ical-generator.mjs';
 // Standalone: node ical-generator.mjs --from-queue --output path/to/schedule.ics
 
@@ -136,7 +136,7 @@ export function generateIcal(events, options = {}) {
   const lines = [
     'BEGIN:VCALENDAR',
     'VERSION:2.0',
-    'PRODID:-//linkedin-thought-leadership//EN',
+    'PRODID:-//linkedin-studio//EN',
     'CALSCALE:GREGORIAN',
     'METHOD:PUBLISH',
   ];
@@ -153,7 +153,7 @@ export function generateIcal(events, options = {}) {
 
     lines.push(
       'BEGIN:VEVENT',
-      `UID:${event.id}@linkedin-thought-leadership`,
+      `UID:${event.id}@linkedin-studio`,
       `DTSTAMP:${now}`,
       `DTSTART;TZID=${tz}:${dtstart}`,
       `DTEND;TZID=${tz}:${dtend}`,