refactor: update multi-agent rules to TMUX & refactor MAM skills scripts

- Update .agents/MULTI_AGENT_RULES.md & .ko.md to align with TMUX concepts
- Add .agents/INSTALL.md guide for MAM setup and workflows
- Clean up legacy markdown reports under .agents/reports/
- Refactor MAM scripts in .agents/skills/ (rename resolve_herdr_session to resolve_herdr_workspace)
- Improve workspace pane splitting/re-use logic in lib.sh
- Reduce paste safety sleep in send_keys_safe and support linking ~/.claude.json

.agents/skills/multi-agent-mux-create/scripts/create_session.sh

@@ -310,7 +310,7 @@ entry = {
     'role': role,
     'herdr_session_created_at': os.environ['NOW_ISO'],
     'herdr_session_epoch': int(epoch) if epoch.isdigit() else 0,
-    'herdr_session': server_name,
+    'herdr_server': server_name,
     'delegate_job_id': os.environ.get('DELEGATE_JOB_ID', '') or None,
     'pane': {
         'index': 0,