Centralize report and evidence period aggregation

[itsDNNS]

What changed

• add one pure, deterministic period aggregation contract for stored DOCSIS snapshots
• preserve duplicate multiplicity and distinguish numeric samples, nulls, unsupported counters, invalid values, and missing samples
• retain stored analyzer and threshold provenance while keeping legacy fallback explicit
• migrate PDF reports, incident reports, complaint text, comparison, and Evidence to the shared aggregate
• load Evidence snapshots once and keep BQM and Connection Monitor as explicit source adapters
• document the dependency boundary and add architecture, determinism, provenance, coverage, and compatibility guards

Compatibility

Existing report, complaint, comparison, and Evidence response shapes remain unchanged. A representative mixed SC-QAM and OFDM fixture produced identical complaint text and normalized PDF text before and after the refactor. There are no database, snapshot, authentication, threshold, locale, or UI migrations.

Validation

• 3818 passed, 2 skipped in the full non-E2E Python suite
• 531 passed in the complete Playwright E2E suite under UTC
• 191 passed in the final focused report, Evidence, comparison, aggregation, and browser gate
• 9 passed in the JavaScript suite
• all 69 locale files validated
• workflow YAML, Python compilation, diff checks, and production dependency audit passed
• deterministic fault proof failed with 8 distinct digests when the same-timestamp content tiebreak was removed, then passed after restoration
• all three representative PDF pages were rasterized and checked for clipping, overlap, overflow, ordering, and null rendering