feat: v2026.3.18 — cleanup, swagger sync, new API endpoints

Remove 21 stale root files (release notes, test files, publish scripts,
improvement docs), .archive/, .git-rewrite/, and outdated docs.
Clean up garbled CONTRIBUTING.md and .npmignore. Simplify root
package.json and README.

Update swagger schema from docs.venice.ai (4566→10050 lines).

New endpoints from swagger:
- Responses API (POST /responses) — Alpha, structured output
- Async video queue (queue/retrieve/quote/complete/transcribe)
- Async audio queue (queue/retrieve/quote/complete)
- Billing balance (GET /billing/balance)
- Billing usage analytics (GET /billing/usage-analytics)

Fixes:
- Image upscale now sends enhance/enhanceCreativity/enhancePrompt/replication
- Audio speech language typed as enum instead of string

All 998 unit tests pass.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: georgeglarson