feat(telemetry): readable Sentry errors, Python tracebacks, and diagnostic mode

Keeps a real, redacted error message instead of "Error: Error", surfaces Python tracebacks in Sentry as a vetted context, and adds an opt-in SNAPOTTER_SENTRY_DIAGNOSTIC verbose mode plus SNAPOTTER_SENTRY_DSN_OVERRIDE. The default fleet path ships nothing on the never-collect list; raw detail is reachable only via the opt-in flag. Also classifies Redis OOM/READONLY replies as operational and removes a ReDoS in stack-frame extraction.

tests/unit/ai/bridge-error.test.ts

@@ -0,0 +1,24 @@
+import { describe, expect, it } from "vitest";
+import { extractPythonErrorInfo } from "../../../packages/ai/src/bridge.js";
+
+describe("extractPythonErrorInfo", () => {
+  it("reads the structured envelope from stdout JSON", () => {
+    const stdout = JSON.stringify({
+      success: false,
+      error: "CUDA out of memory for <path>",
+      errorInfo: {
+        type: "RuntimeError",
+        frames: [{ file: "remove_bg.py", line: 88, func: "run" }],
+      },
+    });
+    const info = extractPythonErrorInfo({ stdout, stderr: "" });
+    expect(info).toEqual({
+      type: "RuntimeError",
+      frames: [{ file: "remove_bg.py", line: 88, func: "run" }],
+    });
+  });
+
+  it("returns null when there is no envelope (back-compat)", () => {
+    expect(extractPythonErrorInfo({ stdout: "boom", stderr: "" })).toBeNull();
+  });
+});