Add Windows-local platform contracts

[scottconverse]

Summary

• adds civiccore.platform contracts for Windows-local module manifests, registry resolution, health summaries, local task envelopes, backup/restore manifests, and installer/runtime action results
• enforces the Windows local profile against required Docker, WSL, Linux shell, and terminal-only runtime paths
• adds the durable PostgreSQL local task queue and worker used by the Windows desktop supervisor for module background jobs
• exports the new platform/task surfaces from the package root and documents the contract/runtime boundary

Verification

• python -m pip install -e .[dev]
• python -m pytest -> 302 passed
• python -m pytest tests\\test_platform_task_queue.py -> 5 passed
• python -m ruff check civiccore tests -> passed
• python -m build -> passed
• git diff --check -> passed
• focused public API/platform smoke -> 13 passed

Audit

• docs/audits/audit-lite-windows-local-platform-contracts-2026-06-13.md
• Unresolved findings: 0 Blocker / 0 Critical / 0 Major / 0 Minor / 0 Nit