flanner 0.3.0

Added

• Claude Code agent integration so plan files reliably land in the managed
  directory with the standard header, without the user reminding Claude:
  • flanner hook guard-write: a PreToolUse hook that denies raw Writes into
    a project's plan directory and steers Claude to create_plan_file_tool
    (fails open; the MCP tools write outside the Write tool so they are never
    blocked)
  • flanner init now writes a managed block into CLAUDE.md and AGENTS.md
    (the cross-tool file Codex reads), merges the guard-write hook into
    .claude/settings.json, and installs a flanner-plan skill