P2: Enterprise policy.json (updates/auth constraints, rollout control)

[Kinin-Code-Offical]

[Kinin-Code-Offical]

Plan

• Add enterprise policy.json support (machine-scope by default) loaded from %ProgramData%\CloudSQLCTL\policy.json or overridden by CLOUDSQLCTL_POLICY_PATH.
• Enforce policy in sensitive commands:
  • upgrade: allow/deny updates; optionally force channel and/or pinned version; block user pin/unpin when policy controls it.
  • �uth: allow/deny login, �dc, and set-service-account; optionally restrict allowed scopes.
• Add docs/Policy.md with schema + examples.
• Add unit tests for policy parsing and enforcement helpers.

Risks

• Over-restricting behavior; keep defaults permissive when policy absent.

Local test plan

• npm ci
• npm run lint
• npm test
• npm run build
• npm run docs:check

[Kinin-Code-Offical]

Done via #45
Merge commit: 14a3711

Verification

• npm ci (PASS)
• npm run lint (PASS)
• npm test (PASS)
• npm run build (PASS)
• npm run docs:check (PASS)