feat(FN-1246): add app version tracking and sync infrastructure

- Add getAppVersion() utility that walks up directories to find package.json
- Add parseSemver() for semver string parsing with major/minor/patch components
- Add CentralCore version sync methods (getAppVersion, syncVersion, getLastSyncTime, getSyncStatus)
- Add CentralCore events for version sync lifecycle (version-sync-started, version-sync-completed, version-sync-failed)
- Add schema v4 migration with appVersion and lastSyncTime columns to projects table
- Export new types (CentralSyncStatus, SyncResult) and utilities via @fusion/core
- Update memory.md documentation with new types
- Fix TypeScript error in app-version.ts (return pkg.version directly instead of cached variable)

packages/core/src/app-version.ts

@@ -0,0 +1,63 @@
+import { readFileSync } from "node:fs";
+import { join, dirname } from "node:path";
+import { fileURLToPath } from "node:url";
+
+/**
+ * Cached app version once resolved.
+ */
+let cachedVersion: string | null = null;
+
+/**
+ * Get the current Fusion application version by reading the nearest package.json.
+ * Walks up from the current file to find the root package.json.
+ * Results are cached for the process lifetime.
+ *
+ * @returns Semver version string (e.g., "0.1.0")
+ */
+export function getAppVersion(): string {
+  if (cachedVersion !== null) return cachedVersion;
+
+  // Start from this file's directory and walk up
+  const __dirname = dirname(fileURLToPath(import.meta.url));
+  let currentDir = __dirname;
+
+  // Walk up to 10 levels looking for package.json
+  for (let i = 0; i < 10; i++) {
+    try {
+      const pkgPath = join(currentDir, "package.json");
+      const pkg = JSON.parse(readFileSync(pkgPath, "utf-8"));
+      if (pkg.version && typeof pkg.version === "string") {
+        cachedVersion = pkg.version;
+        return pkg.version;
+      }
+    } catch {
+      // package.json not found or not parseable — continue walking up
+    }
+    const parentDir = dirname(currentDir);
+    if (parentDir === currentDir) break; // Reached filesystem root
+    currentDir = parentDir;
+  }
+
+  // Fallback if no package.json found
+  cachedVersion = "0.0.0";
+  return cachedVersion;
+}
+
+/**
+ * Parse a semver string into its components.
+ * Supports basic semver format: MAJOR.MINOR.PATCH with optional prerelease suffix.
+ * The string must match the pattern starting from the beginning.
+ *
+ * @param version - Semver version string (e.g., "1.2.3", "1.2.3-beta.1")
+ * @returns Parsed components or null if invalid
+ */
+export function parseSemver(version: string): { major: number; minor: number; patch: number } | null {
+  // Strict semver regex: anchored to start, requires MAJOR.MINOR.PATCH, allows optional prerelease/build
+  const match = version.match(/^(\d+)\.(\d+)\.(\d+)(?:-[0-9A-Za-z.-]+)?(?:\+[0-9A-Za-z.-]+)?$/);
+  if (!match) return null;
+  return {
+    major: parseInt(match[1], 10),
+    minor: parseInt(match[2], 10),
+    patch: parseInt(match[3], 10),
+  };
+}