feat: release process for browser4-cli

[Copilot]

@platonai/browser4-cli had no package scaffold or automated publish pipeline. This PR adds the full release infrastructure.

Package scaffold — sdks/browser4-cli/

• src/cli.ts — Commander-based CLI with session create/close and tool <name> [k=v…] commands; global --base-url / --session-id options
• src/client.ts — thin HTTP client over Browser4's REST/MCP API (createSession, callTool, closeSession)
• src/version.ts — single source of truth for the version string (kept in sync by the release script)
• tests/client.test.ts — 5 unit tests covering construction, session gating, and version consistency
• Standard tooling: tsconfig.json, jest.config.js, .eslintrc.js, .npmignore, README.md, CHANGELOG.md

# Quick usage
SESSION=$(browser4 session create)
browser4 --session-id "$SESSION" tool navigate url=https://example.com
browser4 --session-id "$SESSION" tool aria_snapshot
browser4 session close "$SESSION"

CI release workflow — .github/workflows/publish-cli.yml

Triggered on cli-v* tag push or workflow_dispatch:

build (lint → test → tsc → verify → pack dry-run)
  └─ smoke-test matrix (ubuntu / macos / windows × node 18 / 20)
       └─ publish to npm (--provenance, gated by "npm" environment)
            └─ create GitHub Release  [tag push only]

• Tag format cli-v<X.Y.Z[-pre]> is validated before version extraction
• npm dist-tag (latest / beta / rc / next) auto-inferred from version suffix
• dist/ artefacts uploaded once in build and reused by downstream jobs

Release scripts — bin/release/release-cli.sh / .ps1

./bin/release/release-cli.sh 0.2.0        # stable → published as "latest"
./bin/release/release-cli.sh 0.2.0-rc.1  # pre-release → published as "rc"

Each script validates the version, bumps package.json + version.ts, commits, creates an annotated cli-v<version> tag, and pushes — triggering the workflow above.

bin/release/README.md updated with the new CLI release steps.

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