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_after_write.sh

@@ -141,7 +141,7 @@ while IFS= read -r rel_path; do
   names=$(printf '%s' "$code" | scribe_defs | sort -u | head -12 || true)
   # What this write defined, for the end-of-turn question (milestone 439) —
   # recorded before the arms below, which skip a write that defines nothing.
-  printf '%s\n' "$names" | scribe_written_append "$safe_sid" "$rel_path" "$fresh"
+  printf '%s\n' "$names" | scribe_written_append "$safe_sid" "$rel_path" "$fresh" "$code"
   # Nothing DEFINED in what was written (prose, data, a call-site edit) →
   # nothing to say; the arms are about shapes.
   [ -n "$names" ] || continue