v0.1.0

First public release.

Added

• Execution posture pack: 27 sections covering stance, authorization, verification
  standard, reporting, and precedence, including a per-model clause that weights
  the rule matching each model's own failure mode.
• Budget hook (UserPromptSubmit): reads real context occupancy from the session
  transcript's usage records and injects a reminder at a warning and a critical
  threshold.
• Automatic context window detection from the model id and the largest occupancy
  that model has been observed to reach, cached in ~/.castra-windows.json.
• Guardian hook (PreToolUse): classifies shell commands into four verdicts before
  execution, with a read-only exemption narrow enough that a command containing any
  executing segment is still classified whole.
• Open-loop hook (Stop): refuses to end a turn while .castra/openloops has items.
• castra_notes.py: checkpoints that survive a context window reset.
• castra_guardian.py: the classifier, usable standalone.
• Installer that registers hooks without disturbing existing ones, and backs up
  settings.json before writing.
• 26 checks across three test files, each forcing the condition it verifies.