docs(agents): reconcile .claude/CLAUDE.md source-of-truth wording with .cursorrules

[joshuadarron]

Context

#1213 reworded .cursorrules to a single canonical model: the co-located per-package docs are the source of truth, and apps/vscode/docs/api/ is the assistant-facing integration reference within it (read first when writing integration code).

.claude/CLAUDE.md still carries the OLD wording:

• "These docs are the source of truth for the RocketRide API." (~line 44)
• A duplicated copy of the co-located documentation rule (~lines 57-80).

Proposed change

Apply the same reword to .claude/CLAUDE.md and de-duplicate the co-located rule so the two assistant-instruction files agree on one canonical model.

Refs: PR #1213.

[github-actions]

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