Replace Bootstrap with Tailwind CSS + Alpine.js

- Remove all Bootstrap CSS/JS references from templates
- Add Tailwind CSS v4 with Material Design inspired theme (input.css)
- Compile tailwind.css with standalone CLI (committed to repo)
- Vendor Alpine.js 3.14.9 for reactive UI components
- Rewrite base.html to match µPaaS layout structure
- Rewrite htmlheader.html with Tailwind CSS link
- Rewrite navbar.html with Alpine.js mobile menu toggle
- Convert index.html to Tailwind utility classes
- Convert login.html to Tailwind utility classes
- Convert profile.html to Tailwind utility classes
- Add make css target for Tailwind compilation
- Add footer template with project links

closes #4

Makefile

@@ -1,4 +1,4 @@
-.PHONY: test lint fmt fmt-check check build run dev deps docker clean hooks
+.PHONY: test lint fmt fmt-check check build run dev deps docker clean hooks css
 
 # Default target
 .DEFAULT_GOAL := check
@@ -41,3 +41,6 @@ hooks:
 	@printf '#!/bin/sh\nmake check\n' > .git/hooks/pre-commit
 	@chmod +x .git/hooks/pre-commit
 	@echo "pre-commit hook installed"
+
+css:
+	tailwindcss -i static/css/input.css -o static/css/tailwind.css --minify