feat(ui): add Sentry Browser SDK client-side integration

- Add 3 new config fields for browser SDK sample rates:
  sentry_js_traces_sample_rate (default 0.0),
  sentry_js_replay_session_sample_rate (default 0.0),
  sentry_js_replay_on_error_sample_rate (default 0.1)
- Expose Sentry config to Jinja2 templates via _inject_global_context;
  empty-string DSN normalized to None so {% if sentry_dsn %} guard works
- Load Sentry Browser SDK bundle.tracing.replay.min.js from the official
  Sentry CDN in base.html when SENTRY_DSN is configured, with Sentry.init()
  for error capture, browser tracing and session replay
- Register new JS settings fields in SETTING_METADATA so they appear on the
  admin Settings → Observability page
- Update .env.demo with commented-out examples for SENTRY_JS_* variables
- Update docs/ConfigurationGuide.md and docs/SentrySetup.md with full
  browser SDK documentation, env-specific examples and troubleshooting
- Add TestSentryJsTemplateContext (5 tests) and TestSentryJsConfig (4 tests)

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>
Agent-Logs-Url: https://github.com/christianlouis/DocuElevate/sessions/4a945567-67df-4264-aaed-75eb2e236e9c

app/utils/settings_service.py

@@ -2985,6 +2985,43 @@ SETTING_METADATA = {
         "required": False,
         "restart_required": True,
     },
+    "sentry_js_traces_sample_rate": {
+        "category": "Observability",
+        "description": (
+            "Fraction of browser page-loads captured for client-side Sentry performance tracing (0.0–1.0). "
+            "0.0 (default) disables browser tracing; 1.0 captures every navigation. "
+            "Only active when SENTRY_DSN is set."
+        ),
+        "type": "float",
+        "sensitive": False,
+        "required": False,
+        "restart_required": True,
+    },
+    "sentry_js_replay_session_sample_rate": {
+        "category": "Observability",
+        "description": (
+            "Fraction of sessions recorded by Sentry Session Replay (0.0–1.0). "
+            "0.0 (default) disables session recording; 1.0 records every session. "
+            "Only active when SENTRY_DSN is set."
+        ),
+        "type": "float",
+        "sensitive": False,
+        "required": False,
+        "restart_required": True,
+    },
+    "sentry_js_replay_on_error_sample_rate": {
+        "category": "Observability",
+        "description": (
+            "Fraction of error sessions recorded by Sentry Session Replay (0.0–1.0). "
+            "Defaults to 0.1 (10%) so that errors are captured with replay context "
+            "even when session-level recording is disabled. "
+            "Only active when SENTRY_DSN is set."
+        ),
+        "type": "float",
+        "sensitive": False,
+        "required": False,
+        "restart_required": True,
+    },
 }