fix(ci): Use npm/package-lock.json for cache-dependency-path

The root package-lock.json is in .gitignore, but npm/package-lock.json
is tracked. Update all cache-dependency-path references to use the
tracked lock file for proper npm caching in GitHub Actions.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: ruvnet

.github/workflows/agentic-synth-ci.yml

@@ -47,7 +47,7 @@ jobs:
         with:
           node-version: ${{ env.NODE_VERSION }}
           cache: 'npm'
-          cache-dependency-path: package-lock.json
+          cache-dependency-path: npm/package-lock.json
 
       - name: Install dependencies
         working-directory: ${{ env.PACKAGE_PATH }}
@@ -88,7 +88,7 @@ jobs:
         with:
           node-version: ${{ matrix.node-version }}
           cache: 'npm'
-          cache-dependency-path: package-lock.json
+          cache-dependency-path: npm/package-lock.json
 
       - name: Install dependencies
         working-directory: ${{ env.PACKAGE_PATH }}
@@ -154,7 +154,7 @@ jobs:
         with:
           node-version: ${{ env.NODE_VERSION }}
           cache: 'npm'
-          cache-dependency-path: package-lock.json
+          cache-dependency-path: npm/package-lock.json
 
       - name: Install dependencies
         working-directory: ${{ env.PACKAGE_PATH }}
@@ -198,7 +198,7 @@ jobs:
         with:
           node-version: ${{ env.NODE_VERSION }}
           cache: 'npm'
-          cache-dependency-path: package-lock.json
+          cache-dependency-path: npm/package-lock.json
 
       - name: Install dependencies
         working-directory: ${{ env.PACKAGE_PATH }}
@@ -259,7 +259,7 @@ jobs:
         with:
           node-version: ${{ env.NODE_VERSION }}
           cache: 'npm'
-          cache-dependency-path: package-lock.json
+          cache-dependency-path: npm/package-lock.json
 
       - name: Install dependencies
         working-directory: ${{ env.PACKAGE_PATH }}