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/config.py

@@ -1309,6 +1309,40 @@ class Settings(BaseSettings):
         ),
     )
 
+    # ---------------------------------------------------------------------------
+    # Observability – Sentry Browser JavaScript SDK (client-side)
+    # ---------------------------------------------------------------------------
+    # The same SENTRY_DSN is reused for the browser SDK.  The DSN is a *public*
+    # key in Sentry's model and is intentionally embedded in client-side code.
+    # All three settings below default to 0.0 / disabled so that operators opt-in
+    # to the level of browser monitoring they want.
+    # ---------------------------------------------------------------------------
+    sentry_js_traces_sample_rate: float = Field(
+        default=0.0,
+        description=(
+            "Fraction of browser page-loads captured for client-side performance tracing "
+            "(0.0 – 1.0).  0.0 disables browser tracing; 1.0 captures every navigation. "
+            "Only active when SENTRY_DSN is set."
+        ),
+    )
+    sentry_js_replay_session_sample_rate: float = Field(
+        default=0.0,
+        description=(
+            "Fraction of sessions recorded by Sentry Session Replay (0.0 – 1.0). "
+            "0.0 disables session recording; 1.0 records every session. "
+            "Only active when SENTRY_DSN is set."
+        ),
+    )
+    sentry_js_replay_on_error_sample_rate: float = Field(
+        default=0.1,
+        description=(
+            "Fraction of sessions with an error that will be 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."
+        ),
+    )
+
     @model_validator(mode="before")
     @classmethod
     def strip_outer_quotes(cls, data: Any) -> Any: