fix(ci): Use monorepo root as Docker build context for API

Phase 6.4i requires the API Dockerfile to copy local packages
(lewooogo-brain, lewooogo-data) from the packages/ directory.
Changed build context from 'apps/api' to '.' (root) to allow
the Dockerfile to access the entire monorepo structure.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.github/workflows/deploy-prod.yml

@@ -94,6 +94,8 @@ jobs:
           fi
 
       # ----- Build API Image -----
+      # Phase 6.4i: 必須從 monorepo 根目錄建構 (context: .)
+      # 因為 Dockerfile 需要複製 packages/lewooogo-* 本地套件
       - name: "Build API Image"
         if: ${{ github.event_name == 'push' || inputs.deploy_api }}
         env:
@@ -108,7 +110,7 @@ jobs:
             --build-arg PYPI_INDEX_URL=${{ env.PYPI_INDEX_URL }} \
             --build-arg PYPI_TRUSTED_HOST=${{ env.PYPI_TRUSTED_HOST }} \
             -f apps/api/Dockerfile \
-            apps/api
+            .
           echo "✅ API Image: ${{ steps.meta.outputs.api_image }}"
 
       # ----- Build Web Image -----