feat(ttp): inspector drawer surfaces evidence + rule_id behind each technique

The TTPsObservedSection rollup tells the operator "we saw T1059" but
not why. Click any technique row → side drawer opens listing every
ttp_tag row in scope with the persisted evidence JSON, firing
rule_id / rule_version, source_kind / source_id, confidence, and
created_at. Mirrors the CredentialReuseInspector / BountyInspector
pattern (drawer-backdrop + bd-head/bd-body + kvs grid).

Backend:
- New `GET /api/v1/ttp/tags/by-{scope}/{uuid}/{technique_id}`
  (`scope ∈ {identity, attacker, session}`, optional
  `?sub_technique_id=`, `?limit=` capped to 1000). Returns raw
  TTPTag rows newest-first.
- New `TTPTagDetailRow` Pydantic model + re-export.
- New repo method `list_tags_by_scope_and_technique` on
  TTPMixin (+ abstract on BaseRepository) — single query branched
  on scope; identity scope projects through `Attacker.identity_id`
  the same way `list_techniques_by_identity` does.
- Tests: evidence round-trips, sub_technique filter, JWT-required,
  empty scope, unknown scope rejected.

Frontend:
- New `TTPInspector.tsx` + `TTPInspector.css` (violet accent, slide
  animation, focus-trapped panel matching the existing inspector
  family).
- `TTPsObservedSection`'s TechniqueBar is now click+keyboard
  activatable; clicking opens the inspector for that
  (technique, sub_technique) tuple.

mypy clean. 532 passed in the targeted sweep.

tests/api/ttp/conftest.py

@@ -25,6 +25,7 @@ BY_ATTACKER = _BASE + "/by-attacker/{attacker_uuid}"
 BY_CAMPAIGN = _BASE + "/by-campaign/{campaign_uuid}"
 BY_SESSION = _BASE + "/by-session/{session_id}"
 RULES = f"{_BASE}/rules"
+TAG_DETAILS = _BASE + "/tags/by-{scope}/{uuid}/{technique_id}"
 NAVIGATOR = f"{_BASE}/export/navigator"
 NAVIGATOR_IDENTITY = _BASE + "/export/navigator/identity/{uuid}"