feat(voice): stub voice cache lookup for behavior text (Phase 3)

Add lookup.rs with voiced_behavior() — ready to wire into a behavior-serving
system once one exists (Q-058). Tell behaviors always passthrough (never
re-voiced). Cache miss returns base text (graceful degradation).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

decisions/questions-scope.md

@@ -92,4 +92,12 @@ Game concept, prototype boundaries, production pipeline, and feature decisions.
 
 ---
 
-*14 questions (1 resolved, 3 partially resolved, 10 open). Last updated: 2026-03-05 (Q-011 resolved, Q-034 and Q-037 partially resolved — Where's the Fun? Workshop)*
+### Q-058: Runtime behavior text serving system
+- **Status:** Open
+- **Question:** How should NPC observable behaviors be served to the client at runtime? `NpcBlueprint.observable_behaviors` exists as generator output but no runtime system reads it or sends behavior text to the client. The voice pipeline (D-138) needs an integration point: voice cache lookup replaces base text with re-voiced text before delivery. Needs: which system selects the current behavior, how it's delivered in `ObserverSnapshot`, and how tell behaviors (always passthrough) are distinguished from voiceable behaviors.
+- **Assigned to:** Tyre, SI
+- **Source:** Voice pipeline Spike 2 Phase 3
+
+---
+
+*15 questions (1 resolved, 3 partially resolved, 11 open). Last updated: 2026-03-07 (Q-058 added — voice pipeline Phase 3 dependency)*

decisions/questions.md

@@ -9,7 +9,7 @@ Tracked questions awaiting discussion or resolution. Split by domain, mirroring
 | [questions-architecture.md](questions-architecture.md) | Technical foundation | Q-001, Q-006, Q-009, Q-018, Q-019, Q-020, Q-021, Q-022, Q-023, Q-029, Q-030, Q-046 |
 | [questions-perception.md](questions-perception.md) | Player observation | Q-003, Q-014, Q-016, Q-024, Q-025, Q-026, Q-051, Q-053, Q-054 |
 | [questions-content.md](questions-content.md) | Narrative, NPCs, setting | Q-010, Q-012, Q-013, Q-015, Q-017, Q-028, Q-031, Q-033, Q-040, Q-041, Q-042, Q-043, Q-044, Q-045, Q-047, Q-048, Q-049, Q-050, Q-052, Q-056 |
-| [questions-scope.md](questions-scope.md) | Game concept, prototype | Q-002, Q-004, Q-005, Q-007, Q-008, Q-011, Q-027, Q-032, Q-034, Q-035, Q-036, Q-037, Q-038, Q-039 |
+| [questions-scope.md](questions-scope.md) | Game concept, prototype | Q-002, Q-004, Q-005, Q-007, Q-008, Q-011, Q-027, Q-032, Q-034, Q-035, Q-036, Q-037, Q-038, Q-039, Q-058 |
 
 ## Status Summary