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/telemetry.ts

@@ -0,0 +1,72 @@
+import { invoke } from "@tauri-apps/api/core";
+
+type TelemetryLevel = "info" | "warn" | "error";
+
+const MAX_MESSAGE_LENGTH = 2_048;
+let telemetryEnabled = false;
+let configuration: Promise<unknown> = Promise.resolve();
+
+// Telemetry must never contain repository contents or identifying local data.
+function sanitize(message: string): string {
+  return message
+    .replace(/https?:\/\/\S+/gi, "[url]")
+    .replace(/(?:[A-Za-z]:\\|\/)(?:[^\s<>:"|?*]+[\\/])*[^\s<>:"|?*]*/g, "[path]")
+    .replace(/(token|password|secret|authorization|credential)\s*[:=]\s*\S+/gi, "$1=[redacted]")
+    .replace(/[\w.+-]+@[\w.-]+\.[A-Za-z]{2,}/g, "[email]")
+    .slice(0, MAX_MESSAGE_LENGTH);
+}
+
+export function setTelemetryEnabled(enabled: boolean) {
+  telemetryEnabled = enabled;
+  configuration = invoke("set_telemetry_enabled", { enabled }).catch(() => {});
+}
+
+export function telemetryLog(level: TelemetryLevel, message: string, eventName?: string) {
+  if (!telemetryEnabled) return;
+  void configuration.then(() => invoke("emit_frontend_log", {
+      log: {
+        level,
+        message: sanitize(message),
+        eventName,
+      },
+    }))
+    .catch(() => {
+      // Observability must never interrupt the Git workflow.
+    });
+}
+
+function randomHex(bytes: number): string {
+  const values = new Uint8Array(bytes);
+  crypto.getRandomValues(values);
+  return Array.from(values, (value) => value.toString(16).padStart(2, "0")).join("");
+}
+
+export async function tracedInvoke<T>(command: string, args?: Record<string, unknown>): Promise<T> {
+  if (!telemetryEnabled) return invoke<T>(command, args);
+  const startedAtMs = Date.now();
+  const started = performance.now();
+  const traceId = randomHex(16);
+  const spanId = randomHex(8);
+  try {
+    const result = await invoke<T>(command, args);
+    void configuration.then(() => invoke("emit_frontend_span", {
+      span: { name: command, traceId, spanId, startedAtMs, durationMs: performance.now() - started, success: true },
+    })).catch(() => {});
+    return result;
+  } catch (error) {
+    void configuration.then(() => invoke("emit_frontend_span", {
+      span: { name: command, traceId, spanId, startedAtMs, durationMs: performance.now() - started, success: false },
+    })).catch(() => {});
+    throw error;
+  }
+}
+
+export function installGlobalErrorTelemetry() {
+  window.addEventListener("error", (event) => {
+    telemetryLog("error", event.message || "Unhandled frontend error", "frontend.unhandled_error");
+  });
+  window.addEventListener("unhandledrejection", (event) => {
+    const message = event.reason instanceof Error ? event.reason.message : String(event.reason ?? "Unhandled promise rejection");
+    telemetryLog("error", message, "frontend.unhandled_rejection");
+  });
+}