Module persistence 

Persistence module — SQLite index manager, schema migrations, single-writer task, and audit log. Module skeleton — implemented in later waves.

Modules

audit

Audit logger with SHA-256 hash chain for tamper detection.

index

SQLite index manager — WAL mode, single-writer pattern, schema migrations.

schema

SQLite schema migrations embedded as const strings.

writer

Single-writer task for all SQLite mutations.