fix: gateway install uses --@mosaic:registry flag to preserve npm prefix

Replace temp .npmrc + --userconfig approach with the --@mosaic:registry CLI
flag so the user's real ~/.npmrc (including prefix=/home/user/.npm-global)
is honoured. This eliminates EACCES errors for non-root installs that
relied on a user-level prefix config.

Bump @mosaic/cli and @mosaic/mosaic to 0.0.15.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/cli/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@mosaic/cli",
-  "version": "0.0.14",
+  "version": "0.0.15",
   "repository": {
     "type": "git",
     "url": "https://git.mosaicstack.dev/mosaic/mosaic-stack.git",

packages/cli/src/commands/gateway/daemon.ts

@@ -211,23 +211,10 @@ const GITEA_REGISTRY = 'https://git.mosaicstack.dev/api/packages/mosaic/npm/';
 
 export function installGatewayPackage(): void {
   console.log('Installing @mosaic/gateway from Gitea registry...');
-  // Scope only @mosaic packages to Gitea; all other deps resolve from npmjs normally
-  const npmrcContent = `@mosaic:registry=${GITEA_REGISTRY}\n`;
-  const tmpNpmrc = join(GATEWAY_HOME, '.npmrc');
-  ensureDirs();
-  writeFileSync(tmpNpmrc, npmrcContent);
-  try {
-    execSync(`npm install -g @mosaic/gateway@latest --userconfig=${tmpNpmrc}`, {
-      stdio: 'inherit',
-      timeout: 120_000,
-    });
-  } finally {
-    try {
-      unlinkSync(tmpNpmrc);
-    } catch {
-      // Ignore cleanup failure
-    }
-  }
+  execSync(`npm install -g @mosaic/gateway@latest --@mosaic:registry=${GITEA_REGISTRY}`, {
+    stdio: 'inherit',
+    timeout: 120_000,
+  });
 }
 
 export function uninstallGatewayPackage(): void {

packages/mosaic/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@mosaic/mosaic",
-  "version": "0.0.14",
+  "version": "0.0.15",
   "repository": {
     "type": "git",
     "url": "https://git.mosaicstack.dev/mosaic/mosaic-stack.git",