docs: update ROADMAP with completed quick wins

Moved PageSpeed optimizations from "in progress" to "completed":
- Image optimization pipeline
- Font preloading
- Lazy loading
- Cache headers
- CSS bundle split

Added new completed items:
- Image Optimization Pipeline
- Themed Form Components

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

ROADMAP.md

@@ -337,33 +337,6 @@ This ensures sellers never unknowingly sell at a loss due to Printify price chan
 
 ---
 
-## Quick Wins (Low Effort)
-
-### PageSpeed 100% Score
-**Status:** In progress
-**Effort:** 0.5-1 day
-
-Achieve 100% Google PageSpeed score on all core metrics.
-
-**Completed:**
-- [x] Self-hosted fonts (removed Google Fonts external dependency)
-- [x] Production asset pipeline (minified, gzipped CSS/JS)
-
-**Remaining:**
-- [ ] Add proper image dimensions to all `<img>` tags (CLS)
-- [ ] Preload critical fonts (LCP)
-- [ ] Lazy load below-fold images
-- [ ] Add `fetchpriority="high"` to hero images
-- [ ] Optimise mockup images (resize to actual display sizes, WebP format)
-- [ ] Review and reduce unused CSS (currently 22KB gzipped)
-- [ ] Add cache headers for static assets
-
-**Metrics to hit:**
-- Performance: 100
-- Accessibility: 100
-- Best Practices: 100
-- SEO: 100
-
 ---
 
 ## Medium Features
@@ -514,3 +487,28 @@ The project is currently named `simpleshop_theme` (reflecting its origins as a t
 ### Admin Access Route ✅
 - `/admin` redirects to `/admin/theme` (requires auth)
 - Shop owners can bookmark or type `/admin` to access
+
+### PageSpeed 100% Score ✅
+- Self-hosted fonts (removed Google Fonts external dependency)
+- Production asset pipeline (minified, gzipped CSS/JS)
+- Proper image dimensions on all `<img>` tags (CLS prevention)
+- Critical font preloading via `<link rel="preload">`
+- Lazy loading for below-fold images
+- `fetchpriority="high"` on hero/priority images via `responsive_image` component
+- Responsive image variants (AVIF/WebP/JPEG) via image optimization pipeline
+- Shop CSS reduced from 122KB to 36KB (split bundles)
+- Cache headers (`max-age=31536000, immutable`) on static assets
+
+### Image Optimization Pipeline ✅
+- Oban background job processing for variant generation
+- Responsive `<picture>` element with AVIF/WebP/JPEG sources
+- Only generates sizes ≤ source dimensions (no upscaling)
+- Disk cache for variants (regenerable from DB)
+- Mix task for mockup optimization
+- On-demand JPEG fallback generation
+
+### Themed Form Components ✅
+- Semantic CSS classes (`.themed-input`, `.themed-button`, `.themed-card`, etc.)
+- Phoenix components (`shop_input`, `shop_button`, `shop_card`, etc.)
+- Consistent styling across all shop forms
+- Reduced repeated inline styles