feat(ledger): the consumer map reads transition names and concatenated prefixes (#2970)

Paying down #2962 measured `flag="unused-css"` against a hand audit and
found it had a permanent false-positive floor: roughly sixty classes it
called unused are alive and always would be, because two ordinary authoring
forms produce names no reader of `class=` attributes can see. A flag whose
list you cannot act on line by line is worse than no flag — act on it and
you delete live UI.

- A transition `name=` IS a class reference. `<Transition name="toast">`
  makes Vue apply `.toast-enter-active` and its siblings at runtime, and
  React's `<CSSTransition classNames="fade">` does the same with a different
  suffix set. Every spelling of the tag is read (`Transition`,
  `TransitionGroup`, `transition-group`), and the emitted suffix set is the
  union of Vue 3, Vue 2 and React: naming a class no rule defines costs
  nothing, since it resolves to no row. A bound `:name` stays unknowable.
- A concatenated name contributes its static head as a PREFIX reference.
  `` `status-${s}` ``, `'pri-' + p` and `class="card-{{ v }}"` all leave a
  head behind once the hole is blanked — and `_CLASS_TOKEN_RE` accepts a
  trailing hyphen, so until now the extractor emitted a junk token
  `"status-"` that matched nothing. It is now `status-*`, and
  resolve_consumers credits every row whose symbol starts with that head,
  each under the same own-file-else-fan-out rule as an exact token. `*`
  cannot occur in a class token, so the marker rides the existing
  dict[str, int] with no schema change. A head shorter than two characters
  says nothing and is dropped.

Crediting every candidate row is the honest reading: the template genuinely
does not say which one it built, and the alternative is reporting live rules
as dead. What the map still cannot see is a name assembled in a script —
`classList.add` — which stays deliberately out of scope; the skill, the
`flag=` docstring and the refresh payload docs all say so now.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/test_pattern_coverage.py

@@ -152,6 +152,45 @@ def test_class_references_reads_vue_static_and_dynamic_forms_only():
     }
 
 
+def test_class_references_reads_framework_transition_names():
+    """A transition `name=` is a class reference: the framework applies
+    `.toast-enter-active` and friends at runtime, so a stylesheet that
+    defines them is consumed even though no template spells one out (#2970).
+    Every spelling of the tag counts; a bound `:name` stays unknowable."""
+    refs = class_references(
+        "a/T.vue",
+        '<transition-group name="toast"><div class="toast-item" /></transition-group>',
+    )
+    for suffix in ("-enter-from", "-enter-active", "-leave-to", "-move"):
+        assert refs["toast" + suffix] == 1, suffix
+    assert refs["toast-item"] == 1          # the static attribute still counts
+
+    assert "peek-enter-active" in class_references("a/T.vue", '<Transition name="peek">')
+    assert "g-move" in class_references("a/T.vue", '<TransitionGroup name="g">')
+    # React's CSSTransition names the same idea with a different suffix set
+    react = class_references("a/T.jsx", '<CSSTransition classNames="fade">')
+    assert {"fade-enter-active", "fade-exit-active", "fade-exit-done"} <= set(react)
+    # A bound name is a variable, not a name we can read
+    assert class_references("a/T.vue", '<Transition :name="dyn">') == {}
+
+
+def test_class_references_reads_a_concatenated_name_as_a_prefix():
+    """`status-${s}` cannot be resolved to one class, but its static head is
+    real information: it is emitted as the prefix reference `status-*` so
+    the rows it could have built are not reported unused (#2970). A head too
+    short to mean anything, or a bare separator, says nothing."""
+    vue = (
+        '<div :class="`status-${task.status}`" />'
+        "<span :class=\"['pri-' + p]\" />"
+        '<b class="a-" /><u class="-" />'
+    )
+    assert class_references("a/P.vue", vue) == {"status-*": 1, "pri-*": 1}
+    # a server template interpolating into the middle of a name, same reading
+    assert class_references("t/p.html", '<i class="card-{{ v }}" />') == {"card-*": 1}
+    # an ordinary name never picks up the marker
+    assert class_references("a/P.vue", '<div class="page-header" />') == {"page-header": 1}
+
+
 def test_class_references_reads_react_svelte_and_server_templates():
     tsx = (
         "export function X({ on }: { on: boolean }) {\n"