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>

test/local-echo-basic-test.mjs

@@ -149,9 +149,9 @@ async function main() {
 
     // Enable local echo
     await page.evaluate(() => {
-      const s = JSON.parse(localStorage.getItem('claudeman-app-settings') || '{}');
+      const s = JSON.parse(localStorage.getItem('codeman-app-settings') || '{}');
       s.localEchoEnabled = true;
-      localStorage.setItem('claudeman-app-settings', JSON.stringify(s));
+      localStorage.setItem('codeman-app-settings', JSON.stringify(s));
       window.app?._updateLocalEchoState?.();
     });