fix: render immutable release identifiers

[dzkjdxhbgog]

Fixes #1863

Summary:

• add deployment manifest rendering with immutable release identifiers derived from commit SHA, package version, and image digest
• annotate workload metadata and pod templates with commit/package/image digest plus a stable release id
• keep mutable branch/tag names as secondary source_ref, not the primary release identity
• add release history lookup by immutable release id
• keep current main's Windows test-health fixes for AgentStatus export, optional POSIX resource support, and metrics timer locking

Validation:

• python -m pytest tests\test_deployment_release_identity.py -q
• python -m pytest tests\test_metrics.py tests\test_agent_registry.py -q
• python -m pytest -q
• python -m compileall -q src tests
• git diff --check

Note: python -m flake8 ... could not run because flake8 is not installed in this runner.