[mikemikimike]

Fixes #180

Hugging Face Router is no longer part of the default AI fallback path, so a depleted HF account cannot take production or staging requests through the default chain.

Changes:

• Remove HF from the default smart and fast chains.
• Keep HF available when explicitly named in AI_SMART_CHAIN or AI_FAST_CHAIN.
• Make HF environment settings optional for default startup.
• Keep OCR on Claude only.

Tests:

• bun x tsc --noEmit
• Focused AI streaming, config, and usage report tests
• Biome checks for modified files

Issue: #180

[mikemikimike]

Validation note: I ran the repository-wide test suite on this PR commit. 231 of 253 test files passed, covering 5,379 of 6,056 tests. The 22 failing files and 677 failing tests are existing Windows and tooling baseline issues, including Unix /tmp and path assumptions, missing Python, missing Unix flock, stage QA tooling, and deploy/tooling checks. They are outside the changed AI chain and configuration paths and were not introduced by this PR.

The focused AI streaming, configuration, and usage-report tests passed, as did bun x tsc --noEmit, Biome checks for modified files, and git diff --check.