feat(providers): add Lyceum pay-per-use provider + credit quota tracking

[PixmaNts]

Summary

Adds Lyceum (lyceum.technology) as a first-class OpenAI-compatible, usage-based (pay-per-token, like OpenRouter) inference provider, with a credit-balance quota fetcher.

Lyceum exposes an OpenAI-compatible surface at https://api.lyceum.technology/openai/v1 (/chat/completions, /embeddings, /models) authenticated with a lk_… Bearer key, and a documented credit-balance endpoint for pay-per-use tracking.

What it adds

• Registry entry (registry/lyceum): buildOpenAiCompatibleRegistryEntry with base https://api.lyceum.technology/openai/v1/chat/completions, live /models discovery, passthroughModels. The generic DefaultExecutor handles chat/embeddings — no custom executor or translator needed.
• API-key metadata card + AGGREGATOR_PROVIDER_IDS + PROVIDER_ENDPOINTS.
• Credit quota fetcher (lyceumQuotaFetcher.ts): reads GET /api/v2/external/billing/credits (available_credits / used_credits / remaining_credits), surfaced as a credits window in Dashboard › Limits and quota-aware preflight. Registered via quotaTrackersBatch (keeps chat.ts frozen). Fails open on auth/network/shape errors.
• Usage leaf + dispatcher case + USAGE_FETCHER_PROVIDERS / USAGE_SUPPORTED_PROVIDERS / PROVIDER_LIMITS_APIKEY_PROVIDERS + dashboard label/order.
• Tests: registry-shape assertions (free-tier-providers-wave1-c) + a 16-case quota fetcher/usage suite (parser, Bearer auth, 401/403 & network fail-open, cache TTL, exhaustion, preflight proceed/block, usage rows).
• Docs: changelog fragment, regenerated PROVIDER_REFERENCE.md, provider count 354 → 355 across README / AGENTS / llm.txt (+42 i18n mirrors) / SVGs, and an in-convention file-size-baseline bump for the gateways.ts catalog entry.

Verified live

Confirmed against the real Lyceum API before implementing:

• GET /openai/v1/models → OpenAI {object:"list", data:[{id, owned_by}]} shape.
• POST /openai/v1/chat/completions (lyceum/simple) → HTTP 200, standard OpenAI response + usage.
• GET /api/v2/external/billing/credits → {available_credits, used_credits, remaining_credits, monthly_free_credits, purchased_credits, …} with a lk_ key.

Testing

• tests/unit/lyceum-quota-fetcher.test.ts (16/16) + free-tier-providers-wave1-c lyceum assertions (3/3).
• Regression: free-tier-providers-phase3-integration (10/10), -wave5-integration (4/4), generic-quota-fetcher (10/10), provider-limits-ui (25/25).
• npm run typecheck:core, check:provider-consistency, check:file-size, check:docs-all all clean; new files lint-clean.

[diegosouzapw]

The Lyceum integration itself is solid — 16/16 quota-fetcher tests pass locally, the
fail-open pattern matches the existing OpenRouter/Firecrawl fetchers exactly. One thing
though: your description mentions the provider-count bump across README/AGENTS/llm.txt and
a regenerated PROVIDER_REFERENCE.md, but none of those files are actually in the diff —
that's very likely why Docs Gates / Fast Quality Gates are red on your PR. Could you rerun
gen-provider-reference.ts and push the doc files? Also heads-up: #12462 touches the same
line-area of quotaTrackersBatch.ts (adding its own tracker registration) — whichever of
you two lands second will hit a trivial 2-line conflict there.

[PixmaNts]

Rebased onto release/v3.8.51 after #12462 merged, and addressed the review:

• Ran gen-provider-reference.ts → docs/reference/PROVIDER_REFERENCE.md (live total is now 360 providers on the new base).
• Synced the provider count in README.md, AGENTS.md, llm.txt (+65 locale mirrors via sync-llm-mirrors.mjs), package.json description and the diagram SVGs — these were indeed missing from the original diff.
• Resolved the expected 2-line overlap in quotaTrackersBatch.ts (kept both the LLM Gateway and Lyceum registrations); the shared quota-list files (usage.ts, fetcherProviders.ts, supportedProviders.ts, providerLimits.ts, ProviderLimits/constants.ts) keep both entries.

Local gates green: typecheck:core, check:provider-consistency (360 providers, 0 registry-only), check-file-size, check:docs-counts, check:doc-links, check:fabricated-docs, lyceum 16/16, wave1-c 3/3. The only remaining docs-all failure is the pre-existing check:env-doc-sync base drift (issue #13866), unrelated to this diff. PR is MERGEABLE again.

[diegosouzapw]

Thanks @PixmaNts — merging via the release merge-train. Validated in local merge-train (mt-train10c) on the devbox @ train tip 4d841aa1c740bbaa03868dc0a403c62099a99a42 with the 72 sibling PRs of this batch: typecheck:core, file-size, complexity, cognitive-complexity, changelog-integrity green; changed-area node:test 831/831 (0 failing) and vitest 480/482 — the two reds are autoCombo/provider-family-combos.test.ts timing out at 20s, which reproduces on the PURE release tip under the full vitest suite (and is already tracked by the Release-Green issue #13866), so it is inherited, not this batch's. Merged --admin per merge-gates §3/§4/§7.