#3859: fix(macOS): keep Not configured from snapping back to remote (AI-assisted)

AI-assisted: yes Testing: fully tested locally ## What & Why Bug: From Remote mode, switching **Moltbot runs → Not configured** immediately snapped back to Remote. Cause: `gateway.mode` was removed, but a stale `gateway.remote.url` remained. On reload, the app treated "mode unset + remote url present" as Remote. ## Fix When `connectionMode == .unconfigured`, clear `gateway.remote.url` during config sync so the app does not implicitly re-select Remote mode. ## Test plan - ./scripts/restart-mac.sh --no-sign - cd apps/macos && swift build - Verified the picker stays on **Not configured** after switching from Remote. ## Notes - I understand this change clears `gateway.remote.url` when selecting "Not configured". --- *Rebased from #2628 to resolve merge conflicts* <!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> This PR adjusts macOS config sync to avoid the UI snapping back to Remote after selecting **Not configured**. In `AppState.syncGatewayConfigIfNeeded`, when `connectionMode == .unconfigured` it now clears the persisted `gateway.remote.url` key so that `applyConfigOverrides` won’t infer `.remote` on reload when `gateway.mode` is absent but a stale remote URL remains. Change is localized to macOS app state/config persistence logic (`apps/macos/Sources/Moltbot/AppState.swift`) and aligns with existing behavior where `gateway.mode` is removed when unconfigured. <h3>Confidence Score: 4/5</h3> - This PR looks safe to merge with low risk; it’s a small, targeted config-write change. - The change is localized to the unconfigured branch of config syncing and only removes a single persisted key (`gateway.remote.url`) to prevent unintended mode inference. No API surface changes and minimal control-flow impact; main risk is whether other components relied on the URL being preserved while unconfigured. - apps/macos/Sources/Moltbot/AppState.swift <!-- greptile_other_comments_section --> <!-- /greptile_comment -->