feat(build): add automatic npm dependency management

- Add deps:ensure-npm task to automatically install npm packages when needed
- Configure build, serve, and test tasks to depend on npm dependencies
- Use Task's sources/generates/status for intelligent dependency detection
- Prevents build failures due to missing PostCSS and other npm packages
- Improves developer experience by eliminating manual npm install steps

Taskfile.yml

@@ -13,16 +13,22 @@ tasks:
   # Build tasks
   build:
     desc: Build Hugo site
+    deps:
+      - deps:ensure-npm
     cmds:
       - "{{.HUGO_CMD}} --gc --minify"
 
   build:dev:
     desc: Build Hugo site for development
+    deps:
+      - deps:ensure-npm
     cmds:
       - "{{.HUGO_CMD}}"
 
   serve:
     desc: Start Hugo dev server
+    deps:
+      - deps:ensure-npm
     cmds:
       - "{{.HUGO_CMD}} server"
 
@@ -48,16 +54,22 @@ tasks:
 
   test:build:
     desc: Test Hugo build
+    deps:
+      - deps:ensure-npm
     cmds:
       - "{{.HUGO_CMD}} --gc --minify --logLevel info"
 
   test:markdown:
     desc: Lint markdown files
+    deps:
+      - deps:ensure-npm
     cmds:
       - "{{.NPM_CMD}} run test:markdown"
 
   test:html:
     desc: Validate HTML
+    deps:
+      - deps:ensure-npm
     cmds:
       - "{{.NPM_CMD}} run test:html"
 
@@ -67,6 +79,18 @@ tasks:
       - htmltest
 
   # Development tasks
+  deps:ensure-npm:
+    desc: Ensure npm dependencies are installed
+    sources:
+      - package.json
+      - package-lock.json
+    generates:
+      - node_modules/.package-lock.json
+    cmds:
+      - "{{.NPM_CMD}} install"
+    status:
+      - test -d node_modules
+
   deps:install:
     desc: Install all dependencies
     cmds: