feat(shapes): a component file is a candidate shape in its own right (milestone 439 step 5)

A single-file component defines `.card`, `.title` and a `Props`, never
anything named after itself — so the ledger could not hold "StatusChip is
canon" and could not say a new card was built where one already existed.

- coverage.is_file_unit: a file that RENDERS (its markup names classes, or it
  opens a <script>/<template>/<style> block) and defines nothing named after
  its stem gets one `file` row. Structural, not a framework list: Svelte and
  Vue components qualify, a TSX component already has its function's row, a
  module is accounted for by its definitions. Emitting every file would have
  put every module of every project in the todo at once.
- No body fingerprint on file rows, so an edit never re-asks a judgment.
- `file` is its own form and family; derive grouping skips it (`index`,
  `+page` repeat by convention). Divergence buckets it on its own, so a new
  component where a component canon dominates is a fair question.
- mark_canonicals: a snippet recorded at a path with no symbol makes that
  file row canonical; it still covers no definition inside.
- The write hooks apply the same test before noting a new file for the
  end-of-turn question.

Plugin version minted.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

plugin/hooks/scribe_prior_art.sh

@@ -202,12 +202,13 @@ rule_exclude_q=""
 if [ -n "$session_id" ]; then
   safe_sid=$(printf '%s' "$session_id" | tr -c 'A-Za-z0-9._-' '_')
   # What this write defined, for the end-of-turn question (milestone 439). A
-  # Write onto a path that does not exist yet creates a file — a candidate in
-  # its own right. Written before any server call: the ask at the end of the
-  # turn must not depend on this write's hint having been answered.
+  # Write onto a path that does not exist yet creates a file, which may be a
+  # unit in its own right (see scribe_written_append). Written before any
+  # server call: the ask at the end of the turn must not depend on this
+  # write's hint having been answered.
   fresh=""
   [ -e "$file_path" ] || fresh="new"
-  printf '%s\n' "$shapes" | scribe_written_append "$safe_sid" "$rel_path" "$fresh"
+  printf '%s\n' "$shapes" | scribe_written_append "$safe_sid" "$rel_path" "$fresh" "$code"
   idfile="$state_dir/${safe_sid}.ids"
   syncfile="$state_dir/${safe_sid}.sync.ids"
   derivefile="$state_dir/${safe_sid}.derive.ids"