perf: use sargable (Search ARGument ABLE) range predicates for datetime search filters

[ryuwd]

• apply_search_filters previously used date_trunc() to wrap datetime columns in date_format() (MySQL) / strftime() (SQLite), which prevents the database from using indexes on those columns
• Replaced with range-based comparisons on the raw column (e.g., col >= start AND col < end instead of date_format(col, '%Y-%m-%d') = '2025-08-25')
• All precision levels (YEAR through SECOND) and all comparison operators (eq, neq, gt, lt, in, not in) are handled with index-friendly range predicates

-- Direct comparison (uses index): 0.649s
SELECT count(*) FROM Jobs
WHERE Status = 'Done' AND Site = 'LCG.CERN.cern'
  AND LastUpdateTime > '2025-08-25 15:35:31';

-- date_format() wrapper (full table scan): 12.806s
SELECT count(*) FROM Jobs
WHERE Status = 'Done' AND Site = 'LCG.CERN.cern'
  AND date_format(LastUpdateTime, '%Y-%m-%d %H:%i:%S') > '2025-08-25 15:35:31';

Closes #642

[Copilot]

Pull request overview

This PR optimizes datetime search filter performance by replacing non-sargable date_trunc() function calls with index-friendly range predicates. The old implementation wrapped datetime columns in date_format() (MySQL) or strftime() (SQLite) which prevented database index usage, causing full table scans. The new implementation uses direct range comparisons (col >= start AND col < end) that allow the database to utilize indexes on datetime columns, resulting in significant performance improvements (e.g., 0.649s vs 12.806s in the example provided).

Changes:

• Removed date_trunc() wrapper and import from base.py
• Added three new helper functions to compute datetime period boundaries and build sargable range expressions
• Modified apply_search_filters to use range predicates for all datetime search operations (eq, neq, gt, lt, in, not in) across all precision levels (YEAR, MONTH, DAY, HOUR, MINUTE, SECOND)

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[aldbr]

Oops I don't know what happened but it looks like some of my comments were removed 😅

[aldbr]

LGTM