Description

QualityGateConfig in crates/zeph-memory/src/quality_gate.rs implements the MemReader write quality gate (#3222), but has no corresponding config struct in zeph-config. The feature cannot be enabled or configured via config.toml — there is no [memory.quality_gate] TOML section, and SemanticMemory::with_quality_gate() is never called from src/bootstrap.

The playbook at .local/testing/playbooks/memory-write-gate.md references config.quality_gate.enabled = true but this key does not exist.

Reproduction Steps

1. Search crates/zeph-config/ for QualityGateConfig or quality_gate — no results
2. Search src/ for with_quality_gate targeting SemanticMemory — no results
3. Confirm: 16 unit tests pass in isolation, but feature is dead code in production

Expected Behavior

[memory.quality_gate] TOML section in config, wired into SemanticMemory builder in bootstrap, so users can set enabled = true and adjust threshold.

Actual Behavior

Feature is implemented and tested in isolation but not reachable from any config or bootstrap path.

Environment

• Version: 0.20.1
• Features: full

Logs / Evidence

grep -rn "with_quality_gate\|QualityGate" src/ → only LLM routing quality_gate, not memory write gate
grep -rn "QualityGateConfig" crates/zeph-config/ → no results