* Add skill URI scheme proposal with survey of existing patterns (#44)
Survey 6 existing URI patterns (NimbleBrain, skilljack-mcp, skills-over-mcp,
FastMCP 3.0, Cloudflare well-known RFC, SEP-2076) and propose a recommended
skill:// URI convention for MCP skill resources. Cross-reference from
approaches.md Approach 6.
* Fix URI structure description: skill name is the authority, not a path segment
* Add versioning deferral note and multi-server collision handling
Address PR review feedback: note that versioning is intentionally deferred,
and recommend clients provide a read_resource tool with server name for
disambiguation when multiple servers expose the same skill URI.
