cleanup: remove clawd/openclaw references, fix permissions, add architecture docs

- Replace all ~/clawd and ~/.clawdbot paths with ~/echo-core equivalents
  in tools (git_commit, ralph_prd_generator, backup_config, lead-gen)
- Update personality files: TOOLS.md repo/paths, AGENTS.md security audit cmd
- Migrate HANDOFF.md architectural decisions to docs/architecture.md
- Tighten credentials/ dir to 700, add to .gitignore
- Add .claude/ and *.pid to .gitignore
- Various adapter, router, and session improvements from prior work

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

.gitignore

@@ -15,3 +15,6 @@ bridge/whatsapp/node_modules/
 bridge/whatsapp/auth/
 .vscode/
 .idea/
+credentials/
+.claude/
+*.pid