workspace: pnpm monorepo with api, web, shared

TypeScript 7 strict, ESLint + Prettier, vitest, AGPL-3.0 license.
Decision 0001 records the latest-majors choice and the TS 6 alias.

Task: M0-T1

tsconfig.base.json

@@ -0,0 +1,17 @@
+{
+  "compilerOptions": {
+    "target": "es2024",
+    "lib": ["es2024"],
+    "module": "nodenext",
+    "strict": true,
+    "noUncheckedIndexedAccess": true,
+    "noImplicitOverride": true,
+    "erasableSyntaxOnly": true,
+    "verbatimModuleSyntax": true,
+    "allowImportingTsExtensions": true,
+    "rewriteRelativeImportExtensions": true,
+    "customConditions": ["development"],
+    "skipLibCheck": true,
+    "isolatedModules": true
+  }
+}