[Feature] Allow ?config= override on slash commands for one-off tuning

[akramcodez]

Description

Currently, all per-session overrides (e.g., /context-max, auto-compact thresholds) are CLI-wide once set. Allowing an inline configuration via ?config= (e.g., /compact ?threshold=80) would let users test a value for one command without needing /settings round-trips.

Use Case

Testing temporary configurations for single commands without affecting the global state of the session or requiring tedious settings toggles.

Proposed Solution

Add a generic scope='once' flag or query parameter parsing to the slash command parser, tying into the existing session-override.ts which already supports scoped updates.

Alternatives Considered

Writing full script wrappers or requiring users to toggle the setting back and forth manually.

Additional Context

• I have searched existing issues to ensure this is not a duplicate
• This feature aligns with the project's goals (local-first AI assistance)

Implementation Notes (optional)

session-override.ts already has the plumbing to support temporary overrides. Just map the query string parameters to the command invocation context.

[MayurK-cmd]

Working on this