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/views/base.py

@@ -96,6 +96,21 @@ def _inject_global_context(ctx: dict) -> None:
     )
     ctx.setdefault("enable_factory_reset", getattr(settings, "enable_factory_reset", False))
 
+    # Sentry Browser SDK config (injected into every page so the JS SDK can initialise)
+    # Normalize empty-string DSN to None so the {% if sentry_dsn %} template guard works correctly.
+    _raw_dsn = getattr(settings, "sentry_dsn", None)
+    ctx.setdefault("sentry_dsn", _raw_dsn if _raw_dsn else None)
+    ctx.setdefault("sentry_environment", getattr(settings, "sentry_environment", "production"))
+    ctx.setdefault("sentry_js_traces_sample_rate", getattr(settings, "sentry_js_traces_sample_rate", 0.0))
+    ctx.setdefault(
+        "sentry_js_replay_session_sample_rate",
+        getattr(settings, "sentry_js_replay_session_sample_rate", 0.0),
+    )
+    ctx.setdefault(
+        "sentry_js_replay_on_error_sample_rate",
+        getattr(settings, "sentry_js_replay_on_error_sample_rate", 0.1),
+    )
+
     req = ctx.get("request")
     if req is not None:
         # CSRF token