Support PGLite with local file as DB

## Original Request > enable config to use a local file with PGLite (which might require pgvector wasm compiled) so it can use PostgresSQL without Supabase or a local/hosted version of fullservice PostgresSQL? > > One of the main motivations is to enable running gbrain without requiring external dependency, further reducing adoption barrier — this fits most OpenClaw and Hermes Agent running environment. > > The issue subject should be confined to: "Support PGLite with local file as DB". > > Constraints / preferences: > - PGlite should support every schema feature GBrain uses today, including HNSW indexes and current trigger behavior. > - Socket-bridge mode is good enough. > - If it makes implementation easier, embedded mode can disable multi-worker import at first. > - Preferred on-disk representation: file path, but configurable. ## Agent's Two Cents (could be wrong) > Everything below is the AI agent's best guess based on the current codebase. > Take with a grain of salt — the original request above is the only thing that came from a human. **Suggested priority: p2** ### Problem / Motivation GBrain is currently framed around Supabase / external Postgres. A PGlite local-file mode would let users run GBrain without provisioning a separate database service. That matters because it lowers setup friction, reduces external dependencies, and fits the environments where OpenClaw and Hermes Agent already tend to run. ### What We Checked - `src/core/db.ts` and `src/core/post...