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/perf-audit-first-load.md

@@ -1,7 +1,7 @@
 # Performance Audit: First Page Load
 
 **Date**: 2026-02-18
-**Scope**: Browser first-load of Claudeman web UI (`/`)
+**Scope**: Browser first-load of Codeman web UI (`/`)
 **Method**: Static analysis by 4 parallel audit agents (server, frontend, SSE/xterm, asset pipeline)
 
 ---
@@ -40,7 +40,7 @@ Browser hits /
 │
 │   [FIRST PAINT blocked until ALL CSS downloaded + parsed]
 │
-├── JS executes: new ClaudemanApp().init()
+├── JS executes: new CodemanApp().init()
 │   ├── initTerminal() ................... (SYNC: new Terminal() + terminal.open() → canvas creation)
 │   ├── connectSSE() → /api/events ....... (SSE → fires 'init' with getLightState())
 │   ├── loadState() → /api/status ........ (DUPLICATE #1: same data as SSE init!)