Publish docs/rcp/v1.md — RCP v1.0.0 spec + stability policy

[Narrator]

Sprint 2371 — task T4 (Batch B)

Implements RFC 0001 workstream 4. This is the public artifact IDE-vendor outreach points at.

Scope

• New file docs/rcp/v1.md (distinct from implementation README)
• Documents: MCP tools + prompts surface (final canonical names from T2), wire schemas (ManifestEntry, RuntimeContext, Annotation, error envelopes), example request/response per tool
• Explicit stability policy section: which fields are stable, which are experimental, how additive changes work (minor bump), how breaking changes work (major bump with deprecation window), how alias policy interacts with SemVer
• Cross-link from main README + TECHNICAL_SPEC.md
• Version banner: 'RCP v1.0.0 — published from @domscribe/protocol@1.0.0'

Acceptance

• docs/rcp/v1.md exists and renders cleanly on GitHub
• Stability policy is explicit and falsifiable (a reader can predict what counts as a breaking change)
• Linked from README + TECHNICAL_SPEC
• No drift between doc and @domscribe/protocol Zod schemas (consider generating from schemas)

Depends on

T1 (package exists), T2 (canonical names stamped). Sequence after both land.

Out of scope per RFC 0001

docs/architecture.md ('seven decisions' doc) — separate follow-on.