Add daily-stone page showing a different mineral each day

New dailystone app with 207 minerals scraped from Wikipedia.
Each day displays a different mineral with photos, formula,
properties, description, and history. Page theme color matches
the mineral's typical appearance.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

dailystone/admin.py

@@ -0,0 +1,11 @@
+from django.contrib import admin
+
+from .models import Mineral
+
+
+@admin.register(Mineral)
+class MineralAdmin(admin.ModelAdmin):
+    list_display = ('name', 'formula', 'day_of_year', 'color_hex')
+    list_filter = ('category', 'crystal_system')
+    search_fields = ('name', 'formula')
+    readonly_fields = ('image_urls',)