feat: add custom Bootstrap styling with SCSS support

Implement SCSS-based custom styling system to enable Bootstrap customization while maintaining CDN delivery for core framework.

Changes:
- Add Hugo Pipes SCSS processing pipeline using css.Sass
- Create modular SCSS file structure (main.scss, _variables.scss, _custom.scss)
- Implement custom typography (base font size 1.25rem, adjusted heading sizes)
- Add custom link colors (#0b0089 primary, #0052a3 hover)
- Configure CSS minification and SHA-384 fingerprinting for cache busting
- Add comprehensive SCSS styling documentation

Technical details:
- Updated baseof.html to compile SCSS with Hugo Pipes
- CSS loads after Bootstrap CDN for proper cascade
- Minified output (~154 bytes)
- Supports live reload in development mode

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

openspec/changes/add-custom-bootstrap-styling/proposal.md

@@ -0,0 +1,18 @@
+## Why
+The site currently uses Bootstrap 5.3.2 from CDN with default styling. To establish a unique visual identity and brand consistency, we need the ability to customize Bootstrap variables (font sizes, colors, spacing) and add custom styles without modifying the core framework.
+
+## What Changes
+- Add Hugo SCSS/SASS processing pipeline using Hugo Pipes
+- Create custom SCSS file structure for Bootstrap variable overrides and custom styles
+- Maintain Bootstrap CSS from CDN for core framework
+- Compile custom styles to supplement Bootstrap defaults
+- Enable customization of heading font sizes, link colors, and other design tokens
+
+## Impact
+- Affected specs: `styling` (new capability)
+- Affected code:
+  - `layouts/_default/baseof.html` - Update to include compiled custom CSS
+  - `assets/scss/` - New directory for SCSS files
+  - `hugo.toml` - May need configuration for SCSS processing
+- No breaking changes to existing functionality
+- Performance: Minimal impact, adds one additional CSS file (~few KB)