docs: enhance serve command documentation in BUILDING.md

- Clarify build:web:serve purpose as "production testing"
- Add "Why Use serve?" section explaining benefits
- Document SPA routing support for deep links (/discover, /account)
- Add dedicated "Local Serving with serve" technical section
- Explain server options (npx serve vs Python fallback)
- Improve developer understanding of when and why to use serve

Fixes documentation gap identified in serve command usage

BUILDING.md

@@ -251,7 +251,7 @@ npm run build:web:dev               # Start development server with hot reload
 npm run build:web                   # Development build (starts dev server with hot reload)
 npm run build:web:test              # Test environment build (optimized for testing)
 npm run build:web:prod              # Production build (optimized for production)
-npm run build:web:serve             # Build and serve locally (builds then serves)
+npm run build:web:serve             # Build and serve locally for production testing
 
 # Docker builds
 npm run build:web:docker            # Development build with Docker containerization
@@ -269,6 +269,12 @@ Start the development server using `npm run build:web:dev` or `npm run build:web
 2. The built files will be in the `dist` directory
 3. To test the production build locally, use `npm run build:web:serve` (builds then serves)
 
+**Why Use `serve`?**
+- **Production Testing**: Test your optimized production build locally before deployment
+- **SPA Routing Validation**: Verify deep linking and navigation work correctly (handles routes like `/discover`, `/account`)
+- **Performance Testing**: Test the minified and optimized build locally
+- **Deployment Validation**: Ensure built files work correctly when served by a real HTTP server
+
 You'll likely want to use test locations for the Endorser & image & partner servers; see "DEFAULT_ENDORSER_API_SERVER" & "DEFAULT_IMAGE_API_SERVER" & "DEFAULT_PARTNER_API_SERVER" below.
 
 ### Web Build Script Details
@@ -288,7 +294,7 @@ All web build commands use the `./scripts/build-web.sh` script, which provides:
 - **Clean Build**: Removes previous `dist/` directory
 - **Vite Build**: Executes `npx vite build --config vite.config.web.mts`
 - **Docker Support**: Optional Docker containerization
-- **Local Serving**: Built-in HTTP server for testing builds
+- **Local Serving**: Built-in HTTP server for testing builds with SPA routing support
 
 **Direct Script Usage:**
 
@@ -324,6 +330,25 @@ All web build commands use the `./scripts/build-web.sh` script, which provides:
 - `5` - Serve command failed
 - `6` - Invalid build mode
 
+### Local Serving with `serve`
+
+The `serve` functionality provides a local HTTP server for testing production builds:
+
+**What It Does:**
+1. **Builds** the application using Vite
+2. **Serves** the built files from the `dist/` directory
+3. **Handles SPA Routing** - serves `index.html` for all routes (fixes 404s on `/discover`, `/account`, etc.)
+
+**Server Options:**
+- **Primary**: `npx serve -s dist -l 8080` (recommended - full SPA support)
+- **Fallback**: Python HTTP server (limited SPA routing support)
+
+**Use Cases:**
+- Testing production builds before deployment
+- Validating SPA routing behavior
+- Performance testing of optimized builds
+- Debugging production build issues locally
+
 ### Compile and minify for test & production
 
 - If there are DB changes: before updating the test server, open browser(s) with