feat: evaluate embedding SurrealDB inside the Electron desktop runtime

[ibourgeois]

Context

As a desktop user, I need Katra's local SurrealDB runtime to stay private to the app process when possible so the desktop experience does not depend on exposing a localhost database port on the host machine.

Acceptance Criteria

• Investigate whether Katra can run SurrealDB embedded inside the Electron/Node runtime instead of spawning a host-visible local server.
• Document the architecture tradeoffs between an Electron-embedded runtime and the current localhost CLI-backed runtime.
• Prototype or define a bridge so Laravel can talk to the embedded runtime without requiring a host-visible database port.
• Preserve the separate server-mode story where deployed Katra instances use an external SurrealDB instance or cluster.

Notes

Current SurrealDB docs indicate this is possible in server-side JavaScript:

• Embedding overview: https://surrealdb.com/docs/surrealdb/embedding
• JavaScript embedding: https://surrealdb.com/docs/surrealdb/embedding/javascript
• JavaScript SDK embedding / Node engine with surrealkv://: https://surrealdb.com/docs/sdk/javascript/embedding

Important caveat from the current docs: embedded databases are intended for single-process access. Multi-process or distributed access should still use a remote SurrealDB server.

This issue is specifically about the desktop runtime path. It should not change the broader Katra direction where server deployments use external SurrealDB infrastructure.

Out of Scope

• Replacing the server deployment model with embedded storage.
• General SurrealDB schema design or application-level graph modeling work unrelated to the desktop runtime boundary.