chore: prepare 0.1.0-alpha.1 release

[tensornull]

Summary

Prepare the reviewed manual Registry Alpha release state for 0.1.0-alpha.1:

• record 0.1.0-alpha.1 in the Release Please manifest and remove the one-time release-as bootstrap
• date and normalize the alpha changelog
• approve the exact version for npm publication under next
• mark Registry Alpha as authorized and in progress

This PR does not change the SDK API, package version, or openai:^6.47.0 dependency contract.

Verification

Passed locally on exact commit 8d861bd1c287fa99abfb3bdf0f9c1bbbf5884274:

• npm ci
• npm run verify
• node scripts/validate-release.mjs --tag v0.1.0-alpha.1 --release-prerelease true --require-final --require-releasable-docs
• npm pack --pack-destination .artifacts
• npm run test:package -- --tarball .artifacts/cometapi-0.1.0-alpha.1.tgz --tag v0.1.0-alpha.1
• npm run test:fixtures -- --tarball .artifacts/cometapi-0.1.0-alpha.1.tgz

Retained tarball SHA-512: 2f31f54ad12d26ebe9ccd9bc04e8c7c07e48c4efd5685e2f9e01950381fcb574a073c06665f172b471b525a37cc98f0f3a701d7d1d2536b66d3ef5d7c9b39bbb.

Local verification ran on advisory Node.js 26.3.1. Required GitHub Actions checks provide the blocking Node.js 22 and 24 evidence. No live API request or registry publication is claimed by the local checks.

Checklist

• The change is within the current roadmap milestone.
• Public behavior, compatibility claims, and examples are documented.
• Unit, mocked contract, type, lint, format, build, and package checks pass as applicable.
• Packed ESM, CommonJS, and compatible-OpenAI host fixtures pass as applicable.
• No credential, private prompt, customer data, generated build output, or local dependency directory is included.
• Workflow edits pass the repository-pinned actionlint version.
• Remote Actions, live API, and registry evidence are not claimed from local validation.