fix(autopilot): harden Repo2 deployment configuration and execution

[gmuslia]

Description

Fixes 17 Autopilot and Repo2 findings identified when reviewing changes against commit dd60a96.

Changes

• Fixed regional deployment planning, parallel execution, and bare-stage handling.
• Corrected per-target image, account, region, and deployment fingerprint behavior.
• Wired qualifier, synthesizer, plugins, CI image, npm registry, and ordering configuration through all engines.
• Added required ECR, lookup, and external-ID permissions.
• Improved APP_STAGING and self-mutating pipeline behavior.
• Updated documentation and regression coverage.

Testing

• Unit tests pass (npm run test) — 481 wrapper and 147 CLI tests
• Built locally (npm run build) — jsii and TypeScript compilation passed

Checklist

• Conventional-commit title (fix: address autopilot review findings)
• Breaking changes flagged with feat!: or a BREAKING CHANGE: footer — no breaking changes
• Docs updated if behaviour changed

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license.