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>

src/templates/case-template.md

@@ -18,11 +18,11 @@ Then update the Project Overview section below.
 
 ---
 
-## Claudeman Environment
+## Codeman Environment
 
-This session is managed by **Claudeman** and runs within a tmux session.
+This session is managed by **Codeman** and runs within a tmux session.
 
-**Important**: Check for `CLAUDEMAN_MUX=1` environment variable to confirm.
+**Important**: Check for `CODEMAN_MUX=1` environment variable to confirm.
 - Do NOT attempt to kill your own tmux session
 - The session persists across disconnects - your work is safe
 - Token usage, costs, and background tasks are tracked externally

src/templates/claude-md.ts

@@ -1,7 +1,7 @@
 /**
  * @fileoverview CLAUDE.md template generation
  *
- * Generates CLAUDE.md configuration files for new Claudeman projects.
+ * Generates CLAUDE.md configuration files for new Codeman projects.
  * Reads the bundled case-template.md and performs placeholder substitution.
  * Supports custom templates via settings.json override.
  *