Recover exact rewrite line attribution

[svarlamov]

Summary

• Move exact logical-line recovery into the main rewrite note-shift path so preserved source lines keep attribution even when Git hunks treat the area as replaced.
• Remove the conflict-resolution-only recovery hook and keep conflict working-log merging focused on newly checkpointed resolution lines.
• Update conflict regression tests to assert the precise line-level split: exact surviving AI lines remain AI, replaced lines remain unattributed/non-AI.

Performance impact

• Adds one logical-line diff per rewritten commit/file pair that has Git diff hunks and an authorship note.
• It is bounded to hunked attributed paths only, not every file in the commit or worktree.
• It reuses already-read source notes and the existing batched note write path, so there is no extra note read/write pass.
• It reads immutable commit blobs only, using source and destination paths from diff-tree, including renames. No live worktree reads.

Validation

• task fmt
• task lint
• task test TEST_FILTER=regular_rebase_with_conflict_preserves_ai_notes NO_CAPTURE=true
• task test TEST_FILTER=regular_rebase_conflict NO_CAPTURE=true
• task test TEST_FILTER=pull_rebase_ff NO_CAPTURE=true
• task test TEST_FILTER=human_conflict NO_CAPTURE=true
• task test TEST_FILTER=rebase NO_CAPTURE=true
• task test
• git diff --check