feat(providers): wire CrofAI /usage_api/ into quota preflight, monitor & Limits page

[jeanfbrito]

Summary

Follow-up to #1604 (built-in CrofAI provider). CrofAI exposes a tiny usage endpoint:

```
GET https://crof.ai/usage_api/
Authorization: Bearer
→ { "usable_requests": number | null, "credits": number }
```

• `usable_requests` — daily request bucket on a subscription plan (`null` on pay-as-you-go).
• `credits` — USD credit balance.

This PR wires that endpoint into all three places OmniRoute exposes provider quota data, so a CrofAI connection behaves like the existing GLM / Minimax built-ins out of the box:

1. Quota preflight (`open-sse/services/quotaPreflight.ts`) — opt-in proactive blocking.
2. Quota monitor (`open-sse/services/quotaMonitor.ts`) — runtime snapshot stream.
3. Limits & Quotas dashboard (`/dashboard/limits` → `open-sse/services/usage.ts` switch + `USAGE_SUPPORTED_PROVIDERS` + `PROVIDER_LIMITS_APIKEY_PROVIDERS`) — what the user sees in the UI.

Without all three, a CrofAI key silently never appears under Limits & Quotas even though the live data is available.

Mapping

Account type	Quota label	Block (preflight only) when	`resetAt`
Subscription (`usable_requests` is a number)	Requests Today — remaining count exposed (no fake percent-used bar; daily allotment isn't returned by the API)	`usable_requests <= 0`	next UTC midnight ISO ¹
Pay-as-you-go (`usable_requests === null`)	— (omitted)	`credits <= 0`	n/a
Always	Credits — `unlimited: true`, displayName `Credits: $X.XXXX` (open balance, not a bucket)	n/a	`null`

¹ CrofAI's `/usage_api/` returns no reset timestamp and the docs only say "requests left today". We synthesize the next UTC midnight as a best-guess so the dashboard's existing `formatResetTime` countdown renders (matches Minimax / Bailian cards). Code comment cites the investigation; swap for a real field if Crof ever exposes one.

Files

File	Change
`open-sse/services/crofUsageFetcher.ts` (new)	Quota fetcher with 60s in-memory cache (matches the codex/bailian shape). Exposes `registerCrofUsageFetcher()`, `fetchCrofUsage()`, `parseCrofUsageResponse()`, `invalidateCrofUsageCache()`.
`src/sse/handlers/chat.ts`	Call `registerCrofUsageFetcher()` at module load alongside the existing Codex / Bailian registrations.
`open-sse/services/usage.ts`	Add `getCrofUsage(apiKey)` and a `case "crof":` in `getUsageForProvider`. Returns `Requests Today` (subscription only) + `Credits` quotas using the existing `UsageQuota` shape. Synthesizes `Requests Today.resetAt` as next UTC midnight.
`src/shared/constants/providers.ts`	Append `"crof"` to `USAGE_SUPPORTED_PROVIDERS`.
`src/lib/usage/providerLimits.ts`	Add `"crof"` to `PROVIDER_LIMITS_APIKEY_PROVIDERS` so the apikey path of `isSupportedUsageConnection` accepts it.
`tests/unit/crof-usage-fetcher.test.ts` (new)	9 cases — parser branches, apiKey fail-open, response cache hit, 401 cache eviction, idempotent register call.
`tests/unit/crof-usage.test.ts` (new)	5 cases — allowlist membership, missing apiKey, subscription quota mapping (incl. `resetAt` parses to a future Date within 24h), pay-as-you-go fallback, 401 messaging.

Total: +460 lines, no deletions.

Verification

• `npm run test:unit` — full suite green (3593/3593) including the two new test files. Pushed via the husky pre-push hook.
• Live `GET https://crof.ai/usage_api/\` with a real key returns `{ credits, usable_requests }` and both `parseCrofUsageResponse` (preflight) and `getCrofUsage` (limits page) produce the expected output for both subscription and pay-as-you-go branches.
• In a locally rebuilt image with this PR + feat(providers): add CrofAI as a built-in API-key provider #1604 stacked, a real CrofAI connection appears on `/dashboard/limits` next to the existing GLM / Minimax / Claude Code cards. `Requests Today` shows a live countdown (e.g., `⏱ 0h 39m`) computed from `resetAt = next UTC midnight`.

Notes

• Depends on feat(providers): add CrofAI as a built-in API-key provider #1604 — the registration uses provider id `crof`. Without feat(providers): add CrofAI as a built-in API-key provider #1604 the new switch case and registration are dormant.
• Targeting `release/v3.7.0` to match where feat(providers): add CrofAI as a built-in API-key provider #1604 landed.

[gemini-code-assist]

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[diegosouzapw]

Thanks @diegosouzapw for this great contribution! 🎉 It's now officially merged into the release/v3.7.0 branch and will be part of the next release. We appreciate your effort on adding Image Generation & Editing for ChatGPT Web!