feat: proxy rotation + custom pool selection, API key quota tracker, Tailscale fix

[mahdiwafy]

Summary

This PR supersedes #67 and #73, combining their features with additional improvements:

Features

1. Proxy Rotation with Custom Pool Selection

• Provider-level rotation strategies: none, fill-first, round-robin, random
• NEW: Checkbox grid UI to select a subset of active proxy pools for rotation (instead of rotating across all pools globally)
• pickProxyPoolId() accepts targetProxyPoolIds parameter to filter rotation
• Proxy usage logging: [PROXY] PROVIDER | model | conn=Name | pool=ID | vercel-relay=URL
• Virtual connection injection for no-auth free providers (unified proxy resolution pipeline)

2. API Key Quota Tracker

• getApiKeyUsageSnapshot() returns real-time metrics: rpm, rph, rpd, tokens/5h, tokens/day, tokens/week, tokens/month
• Each metric includes used, limit, percent, and status (ok/warning/danger/blocked)
• Dashboard card grid with status badges, quota progress bars, and summary stats
• In-memory rolling counters (apiKeyCounters.js) to avoid DB write amplification

3. Tailscale Loading Fix

• UI no longer stuck in endless loading when tunnelUrl is empty
• Login pending state shows warning instead of infinite spinner
• clearUserAuth() removed from finally block — buttons remain accessible

Superseded PRs

• feat(proxy): add provider proxy rotation strategy UI #67 (proxy-rotation-strategy): Basic rotation UI — this PR includes those changes plus custom pool subset selection
• feat(keys): add granular API key limits #73 (api-key-limits): Key limits backend — this PR includes those changes plus the quota tracker UI and usage snapshot

Files Changed

File	Changes
connectionProxy.js	pickProxyPoolId with targetProxyPoolIds, resolveConnectionProxyConfig, filterTargetProxyPoolIds
NoAuthProxyCard.js	Rotation strategy selector, checkbox grid for pool subset, conditional UI
auth.js	Proxy pool override, virtual connection injection, API key limit enforcement
EndpointPageClient.js	API key card grid, quota progress bars, status badges, Tailscale loading fix
apiKeyUsageRepo.js	getApiKeyUsageSnapshot, buildMetric helper
providers/[id]/page.js	Render NoAuthProxyCard for all providers
pnpm-lock.yaml	duck-duck-scrape dependency

Test Plan

• Docker image builds (vansrouter:full-merge)
• Container serves 201 models
• oc/deepseek-v4-flash-free chat completion → 200
• Proxy pool logging in container logs
• API key usage snapshot returns correct metrics
• Public domain https://router.mahdiwafy.my.id/v1/models → 200
• Tailscale status endpoint returns valid JSON without hanging

[Vanszs]

Request for revision — please do not treat this as a rejection.

The proxy rotation, no-auth improvements, quota visibility, and Tailscale fixes are relevant to VansRouter. The current PR combines them in a way that changes existing custom behavior and makes the quota feature non-durable.

Please split the PR into focused revisions:

1. Tailscale empty-URL/loading fix;
2. pure proxy-pool selector/rotation helper;
3. no-auth provider rotation UI;
4. API-key quota/limits as a separate persistence-backed feature;
5. unrelated UI cleanup.

Revision requirements:

• Keep connection-level proxy precedence and existing relay/strictProxy/noProxy semantics.
• Do not override an explicit authenticated connection proxy without an explicit migration plan and tests.
• Filter inactive/invalid pools before selection.
• Document process-local rotation behavior or make selection deterministic/shared if required.
• Do not remove RTK, Headroom, Caveman, or Ponytail controls from the endpoint page unless the replacement UI and locale behavior are included and verified.
• API-key limits require schema/migration, repository/API validation, enforcement across modalities, concurrency semantics, persistence, and tests; an in-memory counter alone is not sufficient.

The focused revisions are welcome. Please revise the scope and preserve VansRouter custom proxy and Token Saver behavior.

[mahdiwafy]

Split per your feedback. The proxy rotation part is now its own focused PR:

#87 — fix(proxy): pure proxy-pool selector/rotation helper (connectionProxy.js only, no quota/token-saver/UI)

This PR #77 (combined scope) is superseded. Closing.