release: 1.0.1 — Cleanup & Z-Timestamp Fix

[johnnichev]

Version bump for the 1.0.1 patch. The substantive changes already merged in #151; this rolls the version (1.0.0 -> 1.0.1) and the [Unreleased] changelog into a dated [1.0.1] section.

What 1.0.1 ships:

• Knowledge stores raise on Z-suffixed timestamps (Python 3.10); consolidate ISO-parse into a shared _time.py #136 — knowledge/checkpoint loaders no longer crash on Z-suffixed timestamps on Python 3.10 (the real bug; new _time.parse_iso helper)
• selectools status: CLI computes a status string then prints the wrong variable #135 — selectools doctor prints the status text it computes
• Remove confirmed dead code (unused serve dataclasses, 2 dead helpers, 5 dead locals) #137 — dead code removed (3 dataclasses, 2 helpers, 4 locals, 104 imports)
• Tighten ruff config: enable F841, scope the F401 ignore to __init__.py #138 — ruff F401/F841 enforced repo-wide

All internal; the frozen 1.0 API is unchanged. After merge: tag v1.0.1 -> publish CI -> PyPI.