Add SO3 product sequence filtering utilities

[FlorianPfaff]

Summary

• add generic particle filter result diagnostics
• add product-state partition helpers for block particle filters
• add SO3 product sequence filter utilities and an example
• add focused coverage for partition helpers, particle results, and SO3 sequence filtering

Validation

• Applied patch against current main, skipping smoother files already present upstream
• Checked for conflict markers and .rej files
• Ran git diff --check and git diff --cached --check

Tests were not run per request.

[github-actions]

✅MegaLinter analysis: Success

Descriptor	Linter	Files	Fixed	Errors	Warnings	Elapsed time
✅ COPYPASTE	jscpd	yes		no	no	36.41s
✅ PYTHON	black	8	1	0	0	2.72s
✅ PYTHON	isort	8	3	0	0	0.43s
✅ REPOSITORY	checkov	yes		no	no	32.15s
✅ REPOSITORY	gitleaks	yes		no	no	17.48s
✅ REPOSITORY	git_diff	yes		no	no	0.05s
✅ REPOSITORY	secretlint	yes		no	no	14.06s
✅ REPOSITORY	syft	yes		no	no	2.64s
✅ REPOSITORY	trivy-sbom	yes		no	no	4.22s
✅ REPOSITORY	trufflehog	yes		no	no	23.71s

Notices

📣 MegaLinter 9.5.0 is out! Discover the new features and security recommendations in the release announcement. (Skip this info by defining SECURITY_SUGGESTIONS: false)

See detailed reports in MegaLinter artifacts
Set VALIDATE_ALL_CODEBASE: true in mega-linter.yml to validate all sources, not only the diff

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[github-actions]

Test Results

    10 files  ± 0      10 suites  ±0   2h 44m 32s ⏱️ + 17m 48s
 2 132 tests + 7   2 128 ✅ + 7      4 💤 ±0  0 ❌ ±0 
21 745 runs  +70  18 062 ✅ +70  3 683 💤 ±0  0 ❌ ±0 

Results for commit 91ea1d2. ± Comparison against base commit 17dd358.