feat(providers): manual "Clear cooldown" action in the cooling panel

[patrykkopycinski]

Summary

Adds a per-row "Clear cooldown" button to the Currently cooling panel on the provider detail page, for the case where the quota has already refreshed upstream but OmniRoute still benches the connection — the persisted rate_limited_until is OmniRoute's local lesson from the last 429, not upstream truth.

Problem

The cooldown survives process restarts by design (per-account 429 cascade fix). Until it expires, the connection is skipped by routing — even if the provider quota reset minutes ago. The only existing clear paths are side effects of a successful upstream round-trip:

• Test button (buildCredentialTestStatusUpdate) — clears on success, but preserves scheduled quota windows by design
• Edit modal → re-enter API key — clears only when a key is re-typed and validates

Both demand an upstream round-trip, so the "quota already reset" case had no UI remedy; the user waits out a stale local bench.

Solution

A dedicated, direct action:

• PUT /api/providers/:id with { rateLimitedUntil: null } — first-class in updateProviderConnectionSchema, and the route applies the same defaults that reset backoffLevel → 0
• Optimistic local drop (row leaves the cooling panel immediately), success/error toast, full refetch to reconcile with server truth
• The next request is the real test of the key — if the quota is still exhausted, the 429 handler re-benches it with a fresh timer

Changes

File	Change
useProviderConnections.ts	handleClearCooldown + clearingCooldownId in-flight guard (mirrors retestingId pattern)
CoolingConnectionsPanel.tsx optional onClearCooldown / clearingCooldownId props; button hidden for id-less rows, disabled per-row while clearing
ProviderDetailPageClient.tsx	Wires the handler + in-flight id through to the panel
en.json	clearCooldown, clearCooldownInProgress, clearCooldownTitle, cooldownCleared, failedClearCooldown (with providerText fallbacks, so no hard i18n dependency)

Verification

• npm run typecheck:core — clean
• ESLint on all four touched source files — clean (the two remaining no-unused-vars hits in the tree are pre-existing on base, untouched lines)
• New CoolingConnectionsPanel.test.tsx — 6/6 green (click → handler with row id; disabled + silent while in flight; per-row independence; read-only when handler omitted; no button without connection id; renders nothing when empty)
• Pre-existing tests/unit/ui/CoolingConnectionsPanel.test.tsx — still 3/3 green
• API behavior (PUT {rateLimitedUntil: null} → cooldown + backoff cleared) verified live against a running instance before implementation

Not in scope

• Server-side changes: none. The PUT route already accepts the field; this is purely UI wiring.
• Scheduled quota windows (Kimi weekly, Claude session): intentionally not auto-cleared by this button either — the PUT only clears the persisted cooldown field, it does not override shouldPreserveScheduledQuotaCooldown semantics on the test path.