Move AI execution and credentials into a secure Electron main-process service #36

Goal

Establish the security boundary required for cloud and local providers.

Depends on

• Define a provider-neutral AI client and capability contract #35.

Scope

• Execute provider requests in Electron's main process.
• Replace the renderer's generic fetch-style path with narrow start/abort/event IPC.
• Encrypt stored credentials with Electron safeStorage.
• If secure persistence is unavailable, offer session-only use; never fall back to plaintext storage.
• Keep secrets out of renderer persistence, responses, errors, analytics, and logs.
• For custom endpoints, allow HTTPS generally and HTTP only on loopback; validate redirects and reject unsupported schemes.

Acceptance criteria

• The renderer cannot retrieve a stored secret.
• Requests can stream and be cancelled through narrow IPC.
• Secret save/read/delete flows are tested.
• Endpoint validation and log-redaction tests cover failure paths.
• Current LM Studio behavior is not yet migrated in this issue.