feat(mcp): return structuredContent with a declared outputSchema

[BryanFRD]

Problem

Every tool returns a single text block holding pretty-printed JSON, and no tool declares an outputSchema or returns structuredContent. Neither identifier appears anywhere in packages/.

Representative: packages/mcp/src/tools/orgs.ts:24-50, and the same shape in all ~90 handlers.

Why it matters

The result is already structured data — apiRequest<T> returns a typed object, which the handler then stringifies. The client has to re-parse a text blob to get back what the server already had, with no schema to validate against and no way to tell a JSON payload from a human-readable message. Since SDK 1.10 a tool can declare outputSchema and return structuredContent alongside the text block, and clients that support it get typed results while older clients keep reading the text.

Proposed approach

• Derive the output schemas from the existing response interfaces (UserProfile, ApiTokenResponse, and the per-product equivalents) rather than restating the shapes — a zod schema per response type, with the TS type inferred from it.
• Return both structuredContent and the text block, so no client regresses.
• Start with the high-traffic read tools (list_orgs, list_projects, get_me, list_issues, list_sites) and extend from there; this does not need to be one PR.

Acceptance criteria

• Tools converted so far advertise an outputSchema in tools/list and return matching structuredContent.
• The text block is unchanged for clients that ignore structured output.
• Response types have one definition, not a type plus a hand-written schema that can drift.