chore: rename Claudeman to Codeman

Full product rename across 109 files (~834 occurrences):
- Env vars: CLAUDEMAN_* → CODEMAN_*
- Data dirs: ~/.claudeman/ → ~/.codeman/, ~/claudeman-cases/ → ~/codeman-cases/
- tmux prefix: claudeman- → codeman-
- localStorage: claudeman-* → codeman-*
- Package/CLI: claudeman → codeman
- GitHub repo: Ark0N/Claudeman → Ark0N/Codeman
- systemd service: claudeman-web → codeman-web
- Class: ClaudemanApp → CodemanApp

Migration infrastructure for seamless transition:
- state-store.ts: auto-migrates data directories on startup
- tmux-manager.ts: dual-prefix detection (legacy claudeman- sessions)
- app.js: localStorage key migration (preserves old keys)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/voice-input-plan.md

@@ -56,7 +56,7 @@ The blue-tinted voice button in the accessory bar is distinctive but subtle. Whe
 
 Confirmed by research: Web Speech API is the right choice.
 - **Free, fast (150-300ms interim), trivial complexity**
-- Chrome + Safari = ~70% of users, ~95% of Claudeman's target audience (devs on Chrome)
+- Chrome + Safari = ~70% of users, ~95% of Codeman's target audience (devs on Chrome)
 - Works on localhost without HTTPS
 - Accuracy is adequate for English command dictation
 - Deepgram streaming (Phase 2 optional) only if accuracy complaints arise