Move SealShare onto Livewire Material

Replaces maryUI and daisyUI with nonameweb/livewire-material: the Vibrant
indigo scheme, a system/light/dark theme under sealshare-theme, one top
app bar with the account menu, the upload drop zone and link-ready
moments, M3 fields, dialogs instead of wire:confirm, snackbars instead of
flashed messages, a sortable admin table, and the starter-kit cleanup.
Docker builds assets after Composer; CI drops the Flux step.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01V9NnLxnPp8vaaurb3Z1MFy

docker/dev.Dockerfile

@@ -8,6 +8,9 @@ RUN install-php-extensions \
 # Install Node.js for Vite / frontend asset building
 RUN apk add --no-cache nodejs npm
 
+# Composer, for a checkout without vendor/: the assets import Livewire Material from it
+COPY --from=composer:2 /usr/bin/composer /usr/bin/composer
+
 WORKDIR /app
 
 COPY docker/dev-entrypoint.sh /usr/local/bin/dev-entrypoint.sh