build: add build:core to compile the app-consumable core to dist/ (Phase 5d-2)

tsconfig.build.json emits providers/* + persist (+ their parsing.mjs/types deps)
to dist/ as ESM JS + .d.ts. Output is verified node:sqlite-free and functionally
runnable (parse+persist against an injected db). Foundation for the app importing
the shared core.
> obelisk@0.1.0 build:core
> rm -rf dist && tsc -p tsconfig.build.json; dist/ is gitignored.

tsconfig.build.json

@@ -0,0 +1,11 @@
+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "noEmit": false,
+    "outDir": "dist",
+    "rootDir": "scripts",
+    "declaration": true,
+    "rewriteRelativeImportExtensions": true
+  },
+  "include": ["scripts/providers/**/*.ts", "scripts/persist.ts"]
+}