Add official typed HTTP Client for issue #1

[knqiufan]

Summary

• Add the official @powercontext/client typed HTTP Client for the client / C1 profile: hand-written Fetch transport, runtime request and success validation, and 52 OpenAPI-backed methods.
• Cover every operation against the pinned Python Server as contract reachability: a validated success or an OpenAPI-declared Server error counts. This is not 52 semantic successes.
• Keep a clean install free of native addons. pnpm pack:smoke packs Protocol and Client and imports them in a temporary project.

Docs claim client / C1 only. Runtime, Server, MCP, CLI, and the Python-repository DSH plugin change are out of scope.

Closes #1

Profile and parity

• Profile: client
• Target level: C1
• Related issue: Typed Client transport and 52 methods #1

Checklist

• Does not add a second wire contract
• Does not hand-edit contract/ or conformance/ snapshots
• Generated openapi-types.ts is regenerated from tools/generate-protocol so server-defaulted request fields stay optional
• Baseline bump, if any, is this pull request’s only purpose (none)
• Compatibility: undeclared 2xx is a Server error; malformed UTF-8 success bodies are rejected

Test plan

pnpm format
pnpm lint
pnpm typecheck
pnpm build
pnpm test
pnpm generate:check
pnpm conformance
pnpm pack:smoke

CI quality should run POWERCONTEXT_CLIENT_CALLTHROUGH=1 pnpm test after oracle bootstrap. Confirm Node 22/24 client-matrix and three-OS smoke stay green. Local verification already passed pnpm test:client (including 52/52 call-through) and pnpm pack:smoke.