feat(voice): complete Spike 2 voice pipeline with quality-tested prompt engine

Spike 2 delivers the full voice pipeline: queue → worker pool → sr-voice
child process (stdio JSONL) → cache → disk. Three rounds of quality testing
with Paula, Mellanie, and Gestalt produced iterative prompt improvements.

Prompt engine (prompt_builder.rs):
- Example-based epistemic marker integration (not keyword lists)
- Length-aware Angry tell variant (preserves facts on long content)
- Double-prompt technique: REMEMBER block repeats constraints near OUTPUT:
- Imperative injection framing (composition engine controls frequency)
- Anti-invention constraint ("do not add information not in the input")
- Universal RULES cleaned: worldbuilding moved to culture personas

Worker pool (worker.rs):
- Output post-processor strips after first newline (prevents prompt leakage)
- Watchdog poll loop (1s ticks) replaces blocking sleep for cancel
- Child health check before writing (try_wait)

Test infrastructure:
- voice_pipeline.rs: end-to-end test, auto-detects real sr-voice or mock
- voice_quality_batch.rs: 39 edge-case prompts for quality review
- mock-stdio.sh: Python JSONL mock for CI (no model needed)
- Makefile targets: test-voice-mock, test-voice-real

Quality results (Gemma 2B Q4_K_M, CPU ~13 t/s):
- Epistemic markers: naturally integrated (round 1 comma-lists fixed)
- Tell differentiation: 3/5 working (Nervous, Guarded, Angry)
- Information preservation: ~90% (up from ~70%)
- Prompt leakage: eliminated
- Open: Friendly/RoutineDeviation tells inert (#651), Factual bypass (#650)

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

Makefile

@@ -7,7 +7,7 @@ GODOT := $(shell command -v godot4 2>/dev/null || command -v godot 2>/dev/null)
        pre-pr-server pre-pr-client pre-pr-content \
        fixtures-client fixtures-gauntlet golden-diff golden-update \
        checklist-validate checklist-generate \
-       build-sr-voice run-sr-voice \
+       build-sr-voice run-sr-voice test-voice-mock test-voice-real \
        perf-baseline debug-schedule \
        test-ipc-fixtures test-ipc-protocol test-ipc-integration test-ipc-benchmark \
        screenshot visual-movie test-visual visual-update
@@ -70,6 +70,8 @@ help:
 	@echo "  make serve-sr-voice    Start sr-voice server (ARGS='--model <path>')"
 	@echo "  make run-sr-voice      Submit to sr-voice server (ARGS='generate|batch|benchmark ...')"
 	@echo "  make stop-sr-voice     Stop sr-voice server"
+	@echo "  make test-voice-mock   Test voice pipeline with mock sr-voice"
+	@echo "  make test-voice-real   Test voice pipeline with real sr-voice + Gemma 2B"
 	@echo "  make debug-schedule    Print bevy_ecs schedule graph (diff for PR artifacts)"
 	@echo ""
 	@echo "  GODOT_VERSION=4.6 make setup   Override Godot version"
@@ -368,6 +370,18 @@ stop-sr-voice:
 	@lsof -ti :$(SR_VOICE_PORT) | xargs -r kill 2>/dev/null || true
 	@echo "Stopped sr-voice on port $(SR_VOICE_PORT)"
 
+test-voice-mock:
+	@echo "Running voice pipeline test (mock sr-voice)..."
+	cd server && SR_VOICE_MOCK=1 cargo test --test voice_pipeline -- --nocapture
+	@echo "Results: .tmp/voice-test/results.txt"
+
+test-voice-real:
+	@echo "Running voice pipeline test (real sr-voice + Gemma 2B)..."
+	@test -f server/sr-voice/target/release/sr-voice || { echo "Build sr-voice first: make build-sr-voice"; exit 1; }
+	@test -f server/models/gemma2.gguf || { echo "Model not found: server/models/gemma2.gguf"; exit 1; }
+	cd server && cargo test --test voice_pipeline -- --nocapture
+	@echo "Results: .tmp/voice-test/results.txt"
+
 content-ron:
 	cd tooling/content-converter && cargo build --release
 	tooling/content-converter/target/release/content-converter --input content --output content-ron --verbose