Adds /skills/omniroute*/SKILL.md following the Anthropic skill manifest
spec (frontmatter name/description + self-contained body): chat, image,
tts, stt, embeddings, web-search, web-fetch, mcp, a2a + entry point.
External agents (Claude Desktop, ChatGPT, Cursor, Cline) can fetch one
raw GitHub URL to learn how to call OmniRoute — zero-friction onboarding.
OmniRoute-specific differentiators (mcp + a2a skills) extend the 9router
pattern with 2 extra manifests not present in the reference.
Adds structural lint test (tests/unit/docs/skillManifestsLint.test.ts)
enforcing frontmatter, env-var references, and trigger-phrase quality.
Adds "AI Agent Skills" section to README.md root.
Ref: 9router/skills/ pattern (adapted).
