fix(desktop): don't show providers as configured without real credentials (#13608)

* fix(desktop): don't show providers as configured without real credentials

The desktop settings marked any provider with a persisted settings entry
as Configured, but legacy VS Code migration and empty saves can seed
entries (e.g. qwen-code, sapaicore) holding only a default model and no
credentials. Move the CLI's isProviderSettingsUsable readiness check into
@cline/core, expose it as a computed 'configured' flag on the provider
catalog, and use it in the desktop's isProviderConnected.

Co-authored-by: Saoud Rizwan <saoudrizwan@users.noreply.github.com>

* fix(desktop): resync catalog after saves so Configured badge updates live

Optimistic provider mutations can't know the sidecar-computed 'configured'
flag, so after connecting a keyless provider or saving cloud credentials
(e.g. a Vertex project id) the row stayed 'Not configured' until remount.
Silently refetch the catalog after each successful save, guarded by the
existing generation counter so newer edits discard stale responses.

Co-authored-by: Saoud Rizwan <saoudrizwan@users.noreply.github.com>

* fix(desktop): claim a generation in post-save resync so overlapping refreshes can't apply stale snapshots

Co-authored-by: Saoud Rizwan <saoudrizwan@users.noreply.github.com>

* fix(desktop): bump catalog generation on OAuth login success

Every other optimistic provider mutation claims a new generation; the
OAuth success path didn't, so a catalog load or resync still in flight
could arrive late and overwrite the just-connected state.

Co-authored-by: Saoud Rizwan <saoudrizwan@users.noreply.github.com>

* fix(desktop): resync catalog after OAuth login instead of bare generation bump

The resync claims a new generation (discarding any stale in-flight
response) and its own fetch covers both the new OAuth connection and any
provider saved moments earlier, matching the post-save path.

Co-authored-by: Saoud Rizwan <saoudrizwan@users.noreply.github.com>

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Co-authored-by: Saoud Rizwan <saoudrizwan@users.noreply.github.com>