Directly extends decisions --stale feature. When h5i commit runs, check whether the staged diff touches a line near a previously recorded stale decision. If so, print an inline warning before the commit completes:

⚠ Commit touches src/repository.rs:88 near a stale decision from abc123: "chose JSON over binary"
reason was: reduces parse overhead at startup
Has this reasoning changed? Run h5i decisions --stale for details.

Design

• Line-level matching, not file-level. Uses diff hunk ranges from git2::Patch against the decision's recorded file:line location (±CONTEXT_LINES proximity). File-level matching produces too many false positives on large files.
• Stale-only signal. Modified and Fresh entries are dropped. Only decisions with similarity < 0.5 produce a warning.
• Non-blocking. Errors from the staleness check are swallowed so a bug here never breaks the commit path.

Testing

Two unit tests added:

• fires_when_line_touched — hunk spanning the decision line triggers the warning
• silent_when_far — hunk far from the decision line produces no warning