feat(telemetry): Implement structured telemetry logging and reporting

Adds comprehensive client-side telemetry capabilities for usage, errors, and performance metrics. This includes integrating OpenTelemetry standards into both the frontend (Svelte) and backend (Tauri/Rust) layers to capture events, spans, and system resource utilization.

The implementation ensures that all collected data is privacy-filtered by design, explicitly excluding sensitive information like repository paths, credentials, source code, or email addresses from being logged.

- Updates README with detailed SigNoz telemetry guide
- Adds process metrics collection (CPU/Memory) in Rust backend
- Exposes `setTelemetryEnabled` state management to the frontend

src/lib/components/AnalyticsNoticeDialog.svelte

@@ -30,10 +30,10 @@
       </div>
       <div class="analytics-notice-copy">
         <p>
-          Gitty can send anonymous usage events to Aptabase so crashes, rough edges, and commonly used workflows are easier to improve.
+          Gitty can send anonymous usage events and technical error logs to Aptabase and the self-hosted SigNoz service so crashes, rough edges, and commonly used workflows are easier to improve.
         </p>
         <p>
-          Events do not include repository paths, remote URLs, branch names, commit messages, diffs, file names, credentials, or source code.
+          Telemetry does not include repository paths, remote URLs, branch names, commit messages, diffs, file names, credentials, or source code.
         </p>
       </div>
 
@@ -47,7 +47,7 @@
     </div>
 
     <footer class="dialog-footer analytics-notice-footer">
-      <span class="dialog-footer-info">Privacy-friendly, optional, and limited to product usage events.</span>
+      <span class="dialog-footer-info">Privacy-friendly, optional, and limited to product usage and technical errors.</span>
       <button class="btn-primary" type="button" onclick={() => onContinue(allowAnalytics)}>
         <Check size={16} aria-hidden="true" />
         Continue