A-285: the SDK's lib artifact names its paths, so a change to them is a changed package

The indexer holds an artifact's named paths, and the checker packs the SDK for a
group only when its merge changes one of them.

Builds: design 47 G A-285

Claude-Session: https://claude.ai/code/session_01NcbgfGKaxw984XyAPfLm4h

module.json

@@ -4,7 +4,7 @@
   "slug": "sdk",
   "build": {
     "artifacts": [
-      { "name": "lib", "kind": "package", "language": "typescript", "calls": ["finding-calls"] },
+      { "name": "lib", "kind": "package", "language": "typescript", "paths": ["package.json", "package-lock.json", "tsconfig.json", "src"], "calls": ["finding-calls"] },
       { "name": "go", "kind": "package", "language": "go", "paths": ["go"], "calls": ["finding-calls", "ledger-upkeep-calls", "put-sessions", "sent-objects-calls"] }
     ]
   },