Add multi-image compositions, docker setup, tests, and docs

- Add CompositionImage model with multi-image upload and main image flag
- Add composition endpoints: add-images, set-main-image, delete image, by-created-at filter
- Make contact-us by_category public
- Add 24 API tests covering all endpoints
- Add Dockerfile, docker-compose, entrypoint and docker docs
- Add Persian API docs and update README and Postman collection

Co-authored-by: Cursor <cursoragent@cursor.com>

api/admin.py

@@ -1,5 +1,5 @@
 from django.contrib import admin
-from .models import ContactUs, Composition, Campaign
+from .models import ContactUs, Composition, Campaign, CompositionImage
 
 
 @admin.register(ContactUs)
@@ -24,12 +24,20 @@ class ContactUsAdmin(admin.ModelAdmin):
     )
 
 
+class CompositionImageInline(admin.TabularInline):
+    model = CompositionImage
+    extra = 1
+    fields = ['image', 'is_main', 'created_at']
+    readonly_fields = ['created_at']
+
+
 @admin.register(Composition)
 class CompositionAdmin(admin.ModelAdmin):
     list_display = ['name', 'created_at']
     search_fields = ['name', 'description']
     readonly_fields = ['created_at', 'updated_at']
     date_hierarchy = 'created_at'
+    inlines = [CompositionImageInline]
     
     fieldsets = (
         ('اطلاعات ترکیب', {