feat: bootstrap pnpm workspace (E00-S01)

pnpm 11.23.0 workspace with a committed frozen lockfile, Node engine
restricted to the 24.x line, TypeScript 6.0.3 pinned exactly, strict base
tsconfig, apps/packages/extensions kept as separate workspaces, root
build/test/typecheck commands, and the FIT-001 architecture test rejecting
core-to-extension imports. Minimal CI runs only the root scripts (S05
stages stay out of scope). Closes #58.

packages/core/package.json

@@ -0,0 +1,22 @@
+{
+  "name": "@personal-blog/core",
+  "version": "0.0.0",
+  "private": true,
+  "type": "module",
+  "description": "EPPP application core. Bootstrap placeholder — owns application lifecycle, site identity and content primitives in later stories.",
+  "main": "./dist/index.js",
+  "types": "./dist/index.d.ts",
+  "exports": {
+    ".": {
+      "types": "./dist/index.d.ts",
+      "default": "./dist/index.js"
+    }
+  },
+  "files": [
+    "dist"
+  ],
+  "scripts": {
+    "build": "tsc -p tsconfig.json",
+    "typecheck": "tsc -p tsconfig.json --noEmit"
+  }
+}

packages/core/src/index.ts

@@ -0,0 +1,10 @@
+/**
+ * @personal-blog/core — EPPP application core.
+ *
+ * Bootstrap placeholder. Later EPPP stories replace this module with the real
+ * application core (site identity, content primitives, extension runtime).
+ *
+ * FIT-001: code in this package must never import a concrete extension.
+ * Enforced by tests/architecture.test.ts in CI.
+ */
+export const CORE_VERSION = '0.0.0';

packages/core/tsconfig.json

@@ -0,0 +1,8 @@
+{
+  "extends": "../../tsconfig.base.json",
+  "compilerOptions": {
+    "rootDir": "src",
+    "outDir": "dist"
+  },
+  "include": ["src"]
+}