Preserve indexed event filtering

[brainx]

Summary

• preserve indexed event filtering by assembling queries from fixed internal clause literals
• keep all external filter, cursor, and pagination values parameterized
• retain event ordering, pagination, injection resistance, and subscriber-failure behavior from Fix event-store Bandit baseline #2
• add query-plan coverage for cursor and run-id index searches

Scope

Focused follow-up to #2. No Zeus compatibility, OpenAPI fixture, Kimi, version, or documentation changes.

Verification

• .venv/bin/python -m unittest tests.test_events — 6 tests passed
• bandit -r olymp — zero findings and zero suppressions
• sh scripts/repo_check.sh — 201 tests passed; 85% coverage; formatting, Ruff, mypy, Bandit, and lifecycle checks passed
• sh scripts/wheel_smoke.sh — sdist and wheel built and checked successfully
• git diff --check origin/main...HEAD — passed
• SQLite query plans use the integer primary key for cursor pagination and idx_events_run_id for run filtering
• Hosted CI run 30662013892 — Python 3.11, 3.12, and 3.13 repository checks and wheel smoke passed