feat(realism): wire fingerprint_html/svg through taxonomy + UI

The two new fingerprint canary generators existed at the API level
since f64e78f but weren't visible to the realism engine or the
operator-facing dashboard. Threads them through every place that
enumerates canary content classes.

Backend:
* realism/taxonomy.py - two new ContentClass members
  (CANARY_FINGERPRINT_HTML, CANARY_FINGERPRINT_SVG); enum is
  wire-visible (synthetic_files.content_class column + bus discrim)
  so we add at the bottom, never reorder.
* canary/cultivator.py - class-to-generator dispatch, kind mapping
  (both http), and default placement paths
  (~/Documents/asset_directory.html and network_topology.svg).
* realism/naming.py + bodies.py - _name_canary / _body_canary entries.
* realism/planner.py - added to _DEFAULT_CANARY_CLASS_WEIGHTS and
  the _CANARY_CLASSES classification set.

Frontend:
* decnet_web/src/realism/labels.ts - display labels.
* decnet_web/src/components/RealismConfig/RealismConfig.tsx - default
  canary weight rows so operators see them in the realism config UI.
* decnet_web/src/components/SyntheticFiles/SyntheticFiles.tsx - added
  to the CONTENT_CLASSES allow-list so filter dropdowns show them.

Also: re-applied the nosec B404/B603 markers on canary/obfuscator.py;
the first commit's pre-commit autoformatter stripped them.

Tests: extended tests/realism/test_taxonomy.py's stability assertion
to include the two new values. Full canary + realism suites pass
(362 / 2 skipped).

decnet_web/src/components/RealismConfig/RealismConfig.tsx

@@ -45,6 +45,8 @@ const DEFAULTS: ConfigPayload = {
     { content_class: 'canary_honeydoc_docx', weight: 1 },
     { content_class: 'canary_honeydoc_pdf', weight: 1 },
     { content_class: 'canary_mysql_dump', weight: 1 },
+    { content_class: 'canary_fingerprint_html', weight: 1 },
+    { content_class: 'canary_fingerprint_svg', weight: 1 },
   ],
   canary_probability: 0.03,
 };

decnet_web/src/components/SyntheticFiles/SyntheticFiles.tsx

@@ -52,6 +52,7 @@ const CONTENT_CLASSES = [
   'canary_aws_creds', 'canary_env_file', 'canary_git_config',
   'canary_ssh_key', 'canary_honeydoc', 'canary_honeydoc_docx',
   'canary_honeydoc_pdf', 'canary_mysql_dump',
+  'canary_fingerprint_html', 'canary_fingerprint_svg',
 ] as const;
 
 // ─── Helpers ─────────────────────────────────────────────────────────────────