Ogham 0.3.0

Added

• AgentPolicy::protected_tail_tokens, an optional token-budgeted suffix
  guard for coding-agent transcripts. When set, Ogham keeps every message
  overlapping the estimated trailing token window byte-for-byte across agent
  clearing and budget enforcement; None preserves 0.2.x behavior.

Changed

• Relaxed the rusqlite dependency requirement to >=0.38, <0.41; the
  workspace test suite passes at both range edges.