Rename package to project-manager

- composer.json: aneurin/php-todo-list -> aneurin/php-project-manager
- web/package.json (+ lockfile): "web" -> "project-manager-web"
- docker-compose.yml image tags: php-todo-list -> php-project-manager,
  php-todo-web -> php-project-manager-web

The directory, the Compose project prefix (derived from the directory name),
and the git remote still carry the old name and are left as-is.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

docker-compose.yml

@@ -1,7 +1,7 @@
 services:
   app:
     build: .
-    image: php-todo-list
+    image: php-project-manager
     ports:
       - "8080:80"
     environment:
@@ -44,7 +44,7 @@ services:
   # Without the profile, `docker compose up -d` runs the API alone.
   web:
     build: ./web
-    image: php-todo-web
+    image: php-project-manager-web
     profiles: ["frontend"]
     ports:
       - "5173:5173"