- Make href Optional[str] = None for pattern capabilities
- Remove observe field (v2 architecture observes all hrefs)
- Add rt_filter, match_fn, key_fn fields to Capability
- Add entities default value tuple[()] to Capability
- Add key_override field to BoundEntity
- Update _key() to use key_override when present
- Update _make_observe_paths() to observe all unique hrefs (OBSERVE as accelerator)
- Guard _build() to skip pattern capabilities (href is None)
- Add test_bound_entity_key_override_takes_precedence test
- Update test_capability_defaults to remove observe assertion
All 61 tests passing (60 existing + 1 new).
OCF rt is a schema category shared by many unrelated resources.
The stable unique resource address is the href. Update Capability,
discovery, common capabilities, tests, and plan accordingly.