test(pricing): verify MODEL_COSTS entries and promotional notes

Add tests/test-pricing.ts to assert that known models have non-zero
pricing, promotional deals are documented in comments, and Claude models
include cache pricing. Fix test-pi-local to match against combined
stdout+stderr since pi may output model listing to either stream.

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "pi-commandcode-provider",
-  "version": "0.1.1",
+  "version": "0.2.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "pi-commandcode-provider",
-      "version": "0.1.1",
+      "version": "0.2.0",
       "license": "MIT",
       "dependencies": {
         "@mariozechner/pi-ai": "0.72.0"