[Feature Request] Add session search, tagging, and filtering capabilities

Question

**Bug Description**
Naming and discoverability are weak. You can name sessions, but there's no tagging, no search, no way to say "show me all sessions where I was working on X topic." For a developer resuming a PR, the --from-pr link is clever. For everything else, you're hunting.

**Environment Info**
- Platform: darwin
- Terminal: iTerm.app
- Version: 2.1.153
- Feedback ID: c7527b94-6701-43d4-b803-e04d0ed94e71

**Errors**
```json
[]
```