Normalize MCP tool names — single grammar + alias policy

[Narrator]

Sprint 2371 — task T2 (Batch A)

Closes #18. Implements RFC 0001 workstream 2.

Background

README.md advertises dotted names (domscribe.query.bySource) while TECHNICAL_SPEC.md §3.4 lists dashed names (annotation-get). #18 reports Windsurf rejecting dotted names entirely (^[a-zA-Z0-9_-]{1,64}$). Before stamping RCP v1.0.0 we must canonicalize on one grammar.

Scope

• Staff engineer decides between dotted and underscore form, applying the constraints in RFC 0001 + team memory note on MCP SEP-986
• Document the canonical form + grammar in @domscribe/protocol package README
• Implement alias layer in @domscribe/relay's MCP server: legacy names continue to resolve for ≥1 minor cycle, emit a deprecation warning
• Update every reference: README tool table, TECHNICAL_SPEC §3.4, skills/ content, gemini-extension.json, npx domscribe init MCP config emission, every fixture in domscribe-test-fixtures

Acceptance

• One canonical naming grammar; no mixed dotted/underscore names anywhere in the repo
• Legacy names work via alias layer with deprecation warning
• Windsurf-compatible (test against the regex ^[a-zA-Z0-9_-]{1,64}$)
• Migration note in CHANGELOG referencing the alias window
• MCP tool names use dots, which breaks Windsurf (and likely other clients) #18 referenced and closed by this PR

Depends on

T1 (@domscribe/protocol package exists before names are stamped into it).

Risk

Tool-name rename will break every user's existing .mcp.json if the alias layer is missing or buggy. Test fixtures must include both old and new names resolving correctly.