Release Compass 0.3.21

[forhappy]

Summary

Release Compass 0.3.21 from the exact origin/main base 8ad0021b492a70f9a53c3a949e8924c3c3216429.

Highlights:

• Source-proven Python graph intelligence with artifact-only SCIP enrichment and exact module/stub identities.
• Independently versioned SQLAlchemy, Celery, Django/DRF, FastAPI/Starlette/Pydantic, and Flask framework packs with fail-closed ambiguity handling.
• Bounded DOCX/PPTX/XLSX previews with digest-validated OCR overlays and phase-aware managed model installation.
• Community detail graph physics pauses after settling for a responsive viewer.

Release metadata

• Workspace, package, lockfile, qualification metadata, and VS Code extension versions: 0.3.21.
• Changelog entry: CHANGELOG.md.
• This PR is based directly on the latest origin/main; no unrelated local changes are included.

Validation

Passed locally:

• cargo fmt check
• cargo check --workspace --all-targets --locked
• cargo clippy --workspace --lib --bins --locked -- -D warnings
• cargo test --workspace --lib --bins --locked
• compass CLI product tests
• product-boundary check
• release-script tests
• code-graph qualification (fixtures-only)
• JavaScript typecheck, tests, and viewer asset manifest check

After merge, the tag-triggered compass-release.yml workflow should build and publish the six platform archives, checksums, installers, and release manifest.