feat(graph): daily-digest (יומון) discovery layer (corpus graph PR E)

Chaim's idea: surface the downloaded "כל יום" digests in the graph. Each digest
COVERS the ruling it analyses — a corpus precedent when we have it (16), or a
synthesized gap node from its underlying_citation when we don't (269). So the
digest layer doubles as a discovery signal: it makes visible that the daily
feed overwhelmingly covers rulings NOT yet in the corpus.

Backend (web/graph_api.py — read-only, G2):
- "digest" added to VALID_NODE_TYPES (off by default).
- _digest_nodes_and_edges(): dig:<id> nodes from completed digests, `covers`
  edge → cl:precedent (linked_case_law_id in view) or → gap:<underlying_citation>
  (synthesized, deduped against the gap layer — real in-degree wins). Carries
  concept_tag (label), headline_holding (note), underlying_court/date.
- _add_digests() appends the layer with gap dedup. Wired into both build
  functions. GraphNode += note, digest_id. Gated via node_types (no app.py
  change). Validated: 16 covers→precedent, 269 covers→gap.

Frontend:
- graph.ts: GraphNodeType += "digest"; GraphEdgeType += "covers"; node fields.
- graph-filter-panel: toggle "יומונים (כל יום)" (off by default).
- graph-canvas: digest = teal node (r=4); `covers` edges teal.
- graph-node-panel: digest branch — concept + holding + court/date + link to
  /digests.

web-ui build + lint pass. Invariants: G2 (SELECT-only), UI2. api:types post-deploy.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

web-ui/src/components/graph/graph-node-panel.tsx

@@ -20,6 +20,7 @@ const TYPE_LABELS: Record<string, string> = {
   topic: "נושא",
   practice_area: "תחום",
   gap: "פסיקה חסרה",
+  digest: "יומון",
 };
 
 const GAP_STATUS_LABELS: Record<string, string> = {
@@ -52,6 +53,7 @@ export function GraphNodePanel({
 }) {
   const isPrecedentLike = node.type === "precedent" || node.type === "halacha";
   const isGap = node.type === "gap";
+  const isDigest = node.type === "digest";
   return (
     <Card className="bg-surface border-rule shadow-sm w-80 shrink-0 overflow-y-auto">
       <CardContent className="space-y-4 p-4">
@@ -98,7 +100,19 @@ export function GraphNodePanel({
               </p>
             </>
           )}
-          {!isPrecedentLike && !isGap && (
+          {isDigest && (
+            <>
+              {node.note && (
+                <p className="text-ink text-sm leading-relaxed m-0">{node.note}</p>
+              )}
+              {node.court && <Row label="ערכאה" value={node.court} />}
+              {node.date && <Row label="תאריך" value={node.date.slice(0, 10)} />}
+              <p className="text-ink-muted text-xs leading-relaxed m-0">
+                סיכום יומי מ״כל יום״ — מצביע על הפסיקה שהוא מנתח.
+              </p>
+            </>
+          )}
+          {!isPrecedentLike && !isGap && !isDigest && (
             <p className="text-ink-muted text-xs leading-relaxed m-0">
               לחיצה על נקודה זו מתמקדת בשכניה — כל הפסיקות המשויכות אליה.
             </p>
@@ -122,6 +136,15 @@ export function GraphNodePanel({
             </Link>
           </Button>
         )}
+
+        {isDigest && (
+          <Button asChild variant="outline" className="w-full">
+            <Link href="/digests">
+              <ExternalLink className="size-4 me-2" />
+              לעמוד היומונים
+            </Link>
+          </Button>
+        )}
       </CardContent>
     </Card>
   );