feat: external precedent library with auto halacha extraction

Adds a third corpus of legal authority distinct from style_corpus
(Daphna's prior decisions for voice) and case_precedents (chair-attached
quotes per case). The new corpus holds chair-uploaded court rulings and
other appeals committee decisions, with binding rules (הלכות) extracted
automatically and queued for chair approval.

Pipeline (web/app.py + services/precedent_library.py):
file → extract → chunk → Voyage embed → halacha_extractor → store +
publish progress over the existing Redis SSE channel.

Schema V7 (services/db.py): extends case_law with source_kind +
extraction status fields under a CHECK constraint pinning practice_area
to the three appeals committee domains (rishuy_uvniya, betterment_levy,
compensation_197). New precedent_chunks (vector(1024)) and halachot
tables (vector(1024) over rule_statement, IVFFlat indexes, gin on
practice_areas/subject_tags). Halachot start as pending_review; only
approved/published rows are visible to search_precedent_library.

Agents: legal-writer, legal-researcher, legal-analyst, legal-ceo,
legal-qa get search_precedent_library. legal-writer prompt explains
the three-corpus distinction and CREAC use; legal-qa now verifies that
every cited halacha resolves to an approved row in the corpus.

UI: /precedents page with four tabs — library / semantic search /
pending review (J/K nav, A/R/E shortcuts, badge count) / stats.
Reuses the existing upload-sheet progress + SSE pattern.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

web-ui/src/components/precedents/library-stats-panel.tsx

@@ -0,0 +1,89 @@
+"use client";
+
+import { Skeleton } from "@/components/ui/skeleton";
+import { useLibraryStats } from "@/lib/api/precedent-library";
+import { practiceAreaLabel } from "./practice-area";
+
+function StatCard({ label, value, accent }: { label: string; value: number | string; accent?: boolean }) {
+  return (
+    <div
+      className={`
+        rounded-lg border p-5 bg-surface shadow-sm
+        ${accent ? "border-gold bg-gold-wash/40" : "border-rule"}
+      `}
+    >
+      <div className="text-[0.78rem] text-ink-muted mb-1">{label}</div>
+      <div className={`text-3xl font-bold tabular-nums ${accent ? "text-gold-deep" : "text-navy"}`}>
+        {value}
+      </div>
+    </div>
+  );
+}
+
+export function LibraryStatsPanel() {
+  const { data, isPending, error } = useLibraryStats();
+
+  if (error) {
+    return (
+      <div className="rounded bg-danger-bg border border-danger/40 px-6 py-5 text-danger text-center">
+        {error.message}
+      </div>
+    );
+  }
+
+  if (isPending || !data) {
+    return (
+      <div className="grid grid-cols-2 md:grid-cols-4 gap-3">
+        {[...Array(4)].map((_, i) => <Skeleton key={i} className="h-28 w-full" />)}
+      </div>
+    );
+  }
+
+  return (
+    <div className="space-y-6">
+      <div className="grid grid-cols-2 md:grid-cols-4 gap-3">
+        <StatCard label="פסיקה בקורפוס" value={data.precedents_total} />
+        <StatCard label="הלכות בסך הכל" value={data.halachot_total} />
+        <StatCard
+          label="ממתינות לאישור" value={data.halachot_pending}
+          accent={data.halachot_pending > 0}
+        />
+        <StatCard label="מאושרות (זמינות לסוכנים)" value={data.halachot_approved} />
+      </div>
+
+      <div className="grid md:grid-cols-2 gap-4">
+        <div className="rounded-lg border border-rule bg-surface p-5">
+          <h3 className="text-navy font-semibold mb-3">פילוח לפי תחום</h3>
+          {data.by_practice_area.length === 0 ? (
+            <p className="text-ink-muted text-sm">אין נתונים</p>
+          ) : (
+            <ul className="space-y-2">
+              {data.by_practice_area.map((row) => (
+                <li key={row.practice_area || "—"} className="flex items-center gap-2 text-sm">
+                  <span className="text-ink">{practiceAreaLabel(row.practice_area || null)}</span>
+                  <span className="ms-auto tabular-nums text-navy font-semibold">{row.count}</span>
+                </li>
+              ))}
+            </ul>
+          )}
+        </div>
+
+        <div className="rounded-lg border border-rule bg-surface p-5">
+          <h3 className="text-navy font-semibold mb-3">פילוח לפי רמת תקדים</h3>
+          {data.by_precedent_level.length === 0 ? (
+            <p className="text-ink-muted text-sm">אין נתונים</p>
+          ) : (
+            <ul className="space-y-2">
+              {data.by_precedent_level.map((row) => (
+                <li key={row.precedent_level || "—"} className="flex items-center gap-2 text-sm">
+                  <span className="text-ink">{row.precedent_level || "—"}</span>
+                  <span className="ms-auto tabular-nums text-navy font-semibold">{row.count}</span>
+                </li>
+              ))}
+            </ul>
+          )}
+        </div>
+      </div>
+    </div>
+  );
+}