feat(KB-624): add settings export and import functionality

- Add core settings export/import module with comprehensive tests
- Add CLI commands: kb settings --export and kb settings --import
- Add dashboard API endpoints for settings export/import
- Add dashboard UI for exporting and importing settings in SettingsModal
- Add changeset for @gsxdsm/fusion package release

packages/cli/src/commands/settings-export.ts

@@ -0,0 +1,74 @@
+import { writeFile } from "node:fs/promises";
+import { existsSync } from "node:fs";
+import { resolve, join } from "node:path";
+import { TaskStore, exportSettings, generateExportFilename } from "@fusion/core";
+
+/**
+ * Run settings export command.
+ * Usage: kb settings export [--output <path>] [--scope global|project|both]
+ *
+ * @param options.output - Custom output file path (optional, auto-generates if not provided)
+ * @param options.scope - Which settings to export: 'global', 'project', or 'both' (default: 'both')
+ */
+export async function runSettingsExport(options: {
+  output?: string;
+  scope?: "global" | "project" | "both";
+} = {}): Promise<void> {
+  const store = new TaskStore(process.cwd());
+  await store.init();
+
+  const scope = options.scope ?? "both";
+  const outputPath = options.output;
+
+  try {
+    // Export settings
+    const exportData = await exportSettings(store, { scope });
+
+    // Determine output file path
+    let targetPath: string;
+    if (outputPath) {
+      targetPath = resolve(outputPath);
+    } else {
+      // Generate timestamped filename in current directory
+      const filename = generateExportFilename();
+      targetPath = join(process.cwd(), filename);
+    }
+
+    // Write to file with pretty-printed JSON
+    const jsonContent = JSON.stringify(exportData, null, 2);
+    await writeFile(targetPath, jsonContent);
+
+    // Output success message
+    console.log();
+    console.log(`  ✓ Settings exported to ${targetPath}`);
+    
+    // Show what was exported
+    const parts: string[] = [];
+    if (exportData.global) {
+      const globalKeys = Object.keys(exportData.global).filter(
+        (k) => exportData.global?.[k as keyof typeof exportData.global] !== undefined
+      );
+      if (globalKeys.length > 0) {
+        parts.push(`${globalKeys.length} global setting(s)`);
+      }
+    }
+    if (exportData.project) {
+      const projectKeys = Object.keys(exportData.project).filter(
+        (k) => exportData.project?.[k as keyof typeof exportData.project] !== undefined
+      );
+      if (projectKeys.length > 0) {
+        parts.push(`${projectKeys.length} project setting(s)`);
+      }
+    }
+    
+    if (parts.length > 0) {
+      console.log(`    Exported: ${parts.join(", ")}`);
+    }
+    console.log();
+    
+    process.exit(0);
+  } catch (err) {
+    console.error(`Error: ${(err as Error).message}`);
+    process.exit(1);
+  }
+}