Phase 5: Audit-Spur pro Quelle (ausklappbares Modal)

Backend
- routers/audit.py: GET /api/audit-log nimmt jetzt resource_id als Filter
  (zusätzlich zu resource_type, action, admin_id, from_ts/to_ts).

Frontend
- dashboard.html: modalAudit (Modal) für die Audit-Spur einer Ressource.
- style.css: audit-entry Styles (action-Badge mit Farbcode pro Action-Typ,
  Diff als <details>-Block mit JSON-Pre).
- sources.js:
  - showSourceAudit(id, name) öffnet Modal, lädt /audit-log?resource_type=source&resource_id=...
  - renderAuditEntries: pro Eintrag Action-Badge + Meta (ts/admin/ip) +
    optional ausklappbarer Diff (before/after-JSON)
  - formatDateTime Helper
  - Audit-Button in der Aktionen-Spalte der Grundquellen-Tabelle

src/static/css/style.css

@@ -872,3 +872,65 @@ input[type="date"].filter-select { padding: 6px 10px; }
 .health-badge-ok      { background: rgba(16, 185, 129, 0.15); color: #10b981; }
 .health-badge-unknown { background: rgba(148, 163, 184, 0.15); color: #94a3b8; }
 
+/* === Audit-Spur (Phase 5) === */
+.modal.modal-large {
+    max-width: 720px;
+}
+.audit-content {
+    max-height: 60vh;
+    overflow-y: auto;
+}
+.audit-entry {
+    border: 1px solid rgba(255, 255, 255, 0.08);
+    border-radius: 8px;
+    padding: 10px 12px;
+    margin-bottom: 8px;
+    background: rgba(255, 255, 255, 0.02);
+}
+.audit-entry-head {
+    display: flex;
+    align-items: center;
+    gap: 10px;
+    flex-wrap: wrap;
+    font-size: 13px;
+}
+.audit-entry-action {
+    display: inline-block;
+    padding: 2px 8px;
+    border-radius: 10px;
+    font-size: 11px;
+    font-weight: 600;
+    text-transform: uppercase;
+    letter-spacing: 0.5px;
+}
+.audit-action-create        { background: rgba(16, 185, 129, 0.2); color: #10b981; }
+.audit-action-update        { background: rgba(59, 130, 246, 0.2); color: #3b82f6; }
+.audit-action-delete        { background: rgba(239, 68, 68, 0.2); color: #ef4444; }
+.audit-action-login_success { background: rgba(16, 185, 129, 0.15); color: #10b981; }
+.audit-action-login_failed  { background: rgba(245, 158, 11, 0.15); color: #f59e0b; }
+.audit-action-login_blocked { background: rgba(239, 68, 68, 0.2); color: #ef4444; }
+.audit-entry-meta {
+    color: #94a3b8;
+    font-size: 12px;
+}
+.audit-entry-detail {
+    margin-top: 8px;
+}
+.audit-entry-detail summary {
+    cursor: pointer;
+    font-size: 12px;
+    color: #94a3b8;
+    user-select: none;
+}
+.audit-entry-detail pre {
+    margin: 6px 0 0 0;
+    padding: 8px 10px;
+    background: rgba(0, 0, 0, 0.3);
+    border-radius: 4px;
+    font-size: 11px;
+    line-height: 1.4;
+    overflow-x: auto;
+    color: #e2e8f0;
+    max-height: 240px;
+}
+