feat(session-management): add session defaults store, tools, and session-aware middleware; add tests; update plan doc

- Add in-memory SessionStore (set/get/clear/show)
- New workflow: session-management (session-set-defaults, session-clear-defaults, session-show-defaults)
- Add createSessionAwareTool with requirements preflight and args-over-defaults merge
- Comprehensive tests for tools, store, and factory
- Update session_management_plan.md with DI checklist, commit protocol, and pre-commit hook note

Existing tools unchanged; no remote push.

Author: cameroncooke

.gitignore

@@ -108,3 +108,4 @@ bundled/
 /.mcpregistry_registry_token
 /key.pem
 .mcpli
+.factory