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/central-db.ts

@@ -23,7 +23,7 @@ export { toJson, toJsonNullable, fromJson };
 
 // ── Schema Definition ───────────────────────────────────────────────────
 
-const CENTRAL_SCHEMA_VERSION = 3;
+const CENTRAL_SCHEMA_VERSION = 4;
 
 const CENTRAL_SCHEMA_SQL = `
 -- Projects table (project registry)
@@ -98,6 +98,8 @@ CREATE TABLE IF NOT EXISTS nodes (
   capabilities TEXT,
   systemMetrics TEXT,
   knownPeers TEXT,
+  versionInfo TEXT,
+  pluginVersions TEXT,
   maxConcurrent INTEGER NOT NULL DEFAULT 2,
   createdAt TEXT NOT NULL,
   updatedAt TEXT NOT NULL
@@ -167,6 +169,11 @@ const CENTRAL_SCHEMA_V3_CREATE_PEERS_SQL = CENTRAL_SCHEMA_V3_MIGRATION_SQL
   .filter((line) => !line.trim().startsWith("ALTER TABLE nodes ADD COLUMN"))
   .join("\n");
 
+const CENTRAL_SCHEMA_V4_MIGRATION_SQL = `
+ALTER TABLE nodes ADD COLUMN versionInfo TEXT;
+ALTER TABLE nodes ADD COLUMN pluginVersions TEXT;
+`;
+
 // ── Central Database Class ────────────────────────────────────────────────
 
 export class CentralDatabase {
@@ -222,6 +229,16 @@ export class CentralDatabase {
       migrated = true;
     }
 
+    if (currentVersion < 4) {
+      if (!this.hasColumn("nodes", "versionInfo")) {
+        this.db.exec("ALTER TABLE nodes ADD COLUMN versionInfo TEXT");
+      }
+      if (!this.hasColumn("nodes", "pluginVersions")) {
+        this.db.exec("ALTER TABLE nodes ADD COLUMN pluginVersions TEXT");
+      }
+      migrated = true;
+    }
+
     if (migrated) {
       this.db
         .prepare("INSERT INTO __meta (key, value) VALUES ('schemaVersion', ?) ON CONFLICT(key) DO UPDATE SET value = excluded.value")