Handle policy_rejected status (Anthropic April 4 billing change)

- anthropic-teams.js: detect HTTP 400 extra-usage policy blocks, return
  status='policy_rejected' with quota headers still readable
- report.js: display policy_rejected as CRITICAL with 'POLICY BLOCKED' label
- getSeverity: treat policy_rejected as critical

Currently the direct API (used by monitor) returns 200; pi's OAuth path
returns 400. This fix future-proofs against the block extending to direct
API calls, and correctly classifies the status if it does.

Refs: trentuna/commons#17, trentuna/token-monitor#4

package-lock.json

@@ -0,0 +1,15 @@
+{
+  "name": "token-monitor",
+  "version": "0.1.0",
+  "lockfileVersion": 3,
+  "requires": true,
+  "packages": {
+    "": {
+      "name": "token-monitor",
+      "version": "0.1.0",
+      "engines": {
+        "node": ">=18"
+      }
+    }
+  }
+}