MainsKeeper 0.2.3 — History filter corrections (source-only)

Scope: two History defects only. Prior 0.2.1–0.2.2 Battery Assurance fixes preserved.

1. manualAssuranceHtml normalizes site/ups "all" → null (same as sel.history).
2. manualHistoryRecords: date-only uses calendar-day interval overlap; datetime keeps point rule; undated occurrence never uses recordedAt/receivedAt as occurrence.

Verification:
- Syntax checks: pass
- state-checks.js: 294 passed · 0 failed (group 12 covers 0.2.3)
- Browser verification and screenshots skipped by user request. Visual and browser-interaction acceptance remain unverified.

Historical: REVIEW-0.2.2.txt / state-checks-0.2.2.txt remain the 0.2.2 record (277 passed).