feat: Phase 0 workspace, spikes, and golden harness

Stand up the monorepo skeleton and land the first Phase 0 artifacts:
pairing threat model, plugin catalog, builder detect, 20-prompt golden
harness, and synthetic 2GB mirror timing.

tsconfig.base.json

@@ -0,0 +1,17 @@
+{
+  "compilerOptions": {
+    "target": "ES2022",
+    "module": "Node16",
+    "moduleResolution": "Node16",
+    "strict": true,
+    "noUncheckedIndexedAccess": true,
+    "exactOptionalPropertyTypes": true,
+    "skipLibCheck": true,
+    "esModuleInterop": true,
+    "forceConsistentCasingInFileNames": true,
+    "resolveJsonModule": true,
+    "isolatedModules": true,
+    "declaration": true,
+    "sourceMap": true
+  }
+}