Add guided publish flow and make review notes use note.md

[stefanvictora]

What to build

Make bare revpack publish the primary human-guided publish flow. It should summarize publishable review material, show review state separately, let the user intentionally choose what to publish, and make note.md / publish note the primary review-note contract while still accepting legacy review.md output.

Acceptance criteria

• revpack publish without a subcommand shows a compact interactive summary of publishable review material: findings, replies, summary, and review note.
• Review state is shown separately from review material, with checkpoint selectable when appropriate.
• Empty review notes are visible as empty/skipped but are not selectable.
• A checkpoint-only guided publish is possible when there is no pending review material but the checkpoint is missing or outdated.
• If the active bundle is stale, guided publish warns that pending outputs may describe older code and does not select checkpoint by default.
• revpack publish all keeps its existing behavior, including checkpoint publishing.
• Fresh bundles generate .revpack/outputs/note.md as the primary review-note output.
• revpack publish note is the primary command for publishing a review note.
• Legacy .revpack/outputs/review.md is still read when note.md is absent or empty.
• revpack publish review remains a compatibility alias.
• Status, generated instructions, command help, README/docs, tests, and changelog use the new primary review-note terminology where user-visible.

Blocked by

None - can start immediately