feat(ui): AuditDrilldownDrawer with JSON/SQL render, cURL, drill-back, redaction badges (#23 M7)

Implements Bundle C (M7-T4 through M7-T8) of the Audit Log #23 M7
Central UI work: a right-side off-canvas drawer that opens from
AuditResultsGrid row clicks and renders one AuditEvent in full.

Cohesive single-component delivery:
- Read-only fields stacked (form-layout memory): Channel/Kind, Status,
  HttpStatus, Target, Actor, Source* provenance, CorrelationId,
  OccurredAtUtc, IngestedAtUtc, DurationMs.
- Channel-aware body renderer: DbOutbound {sql, parameters} payloads
  render a code-block with CSS-only .language-sql class plus a
  parameter <dl>; other channels JSON-pretty-print when parseable and
  fall back to verbatim <pre>.
- Redaction badges on Request/Response when the body contains the
  <redacted> or <redacted: redactor error> sentinels.
- Copy-as-cURL (API channels only) builds a curl command from Target
  + optional {method, headers, body} RequestSummary JSON and writes
  it via navigator.clipboard.writeText.
- Show-all-events drill-back navigates to /audit/log?correlationId={id}
  when the event carries a CorrelationId.
- Close button + backdrop-click both raise OnClose.

AuditLogPage wires Event/IsOpen/OnClose; row clicks now open the
drawer (HandleRowSelected pins _selectedEvent + _drawerOpen=true).

11 bUnit tests cover field rendering, JSON pretty-print, verbatim
fallback, SQL block, conditional buttons, redaction badges,
navigation drill-back, and clipboard interop. No third-party UI
libraries: Bootstrap offcanvas + scoped razor.css only.

src/ScadaLink.CentralUI/Components/Audit/AuditDrilldownDrawer.razor.css

@@ -0,0 +1,40 @@
+/* Audit Log drilldown drawer (#23 M7 Bundle C).
+   The base offcanvas + backdrop classes come from Bootstrap. The local
+   overrides below pin our preferred width and pre-block behaviour. */
+
+.audit-drilldown-drawer {
+    /* Slightly wider than the parked-messages drawer because audit rows can
+       carry larger JSON bodies and SQL blocks. Clamp to viewport so narrow
+       windows still get the close button on screen. */
+    width: min(720px, 95vw);
+}
+
+.audit-drilldown-drawer .drawer-pre {
+    /* Wrap long lines and bound the per-block height so the drawer body
+       stays scrollable end-to-end instead of pushing the action buttons
+       below the fold. */
+    white-space: pre-wrap;
+    word-break: break-word;
+    max-height: 320px;
+    overflow-y: auto;
+    margin: 0;
+    font-size: 0.8125rem;
+}
+
+.audit-drilldown-drawer .drawer-pre.json {
+    /* JSON blocks get a faint left rule so they read as quoted material. */
+    border-left: 3px solid var(--bs-info-border-subtle);
+}
+
+.audit-drilldown-drawer .drawer-pre code.language-sql {
+    /* CSS-only highlight cue: SQL stays mono with a hint of bold weight on
+       a slightly different background so the SQL block reads distinct from
+       generic JSON pretty-prints without loading a syntax-highlighter JS
+       library. */
+    font-family: var(--bs-font-monospace);
+    color: var(--bs-emphasis-color);
+}
+
+.audit-drilldown-drawer .drawer-footer {
+    background-color: var(--bs-tertiary-bg);
+}