Update SDK links/wiki to point to rdcp-protocol docs

[mojoatomic]

Goal
Update SDK documentation to reference the canonical protocol site (rdcp.dev) and prevent link rot.

Scope

• Update README and package docs links from old protocol locations to rdcp-protocol (docs + API).
• Create stub wiki pages in rdcp that link to equivalent protocol pages.
• Run/enable link check to guard against regressions.

Acceptance criteria

• All SDK docs/READMEs link to rdcp-protocol pages.
• Stub wiki pages exist and are discoverable.
• Link check passes in CI.

Tracking

• Part of Separate protocol specification from SDK implementation into distinct repositories #111
• Protocol side: Compliance kit for cross-language self-certification rdcp-protocol#3, ci: build otel-plugin before tests; explicit plugin install #5, ci: build root and link @rdcp/server before building otel-plugin #6