Release 0.4.2: tag-index invalidation perf, Redis TTL pushdown, invalidate CLI

[jolovicdev]

Summary

• Perf: delete_by_tags in SQLite batches all matching rows into a single DELETE with one orphan-detection pass — previously O(n) row-by-row _delete_commit_body calls with per-row orphan queries.
• Perf: delete_by_tags in Redis now uses tag-set indexes (cashet:tag:{key}, cashet:tag:{key}:{value}) with SINTER — previously a full zrevrange(all) scan fetching every commit.
• Perf: find_by_fingerprint in Redis pushes TTL filtering server-side via ZREVRANGEBYSCORE using expires_at timestamp as the sorted-set score — previously Python-iterated all candidates checking expires_at client-side.
• Feat: cashet invalidate -t key=value / -t key CLI command.
• Test: replaced time.sleep with freezegun in 3 TTL/GC tests for deterministic execution.
• Test: added Redis delete_by_tags coverage (exact match, bare key, multi-condition) and CLI invalidate tests.

Test plan

• uv run ruff check src/ tests/ && uv run pyright src/
• uv run pytest tests/ -v (339 passed)
• Smoke: pip install ., cashet invalidate -t key=value works