merge: resolve v1.23.0 upstream conflicts, preserve custom git provider config

Resolved conflicts in 8 files by taking upstream refactored code:
- desktop.ts: re-export DesktopSettings from registry
- openchamberConfig.ts: simplified project setup client
- persistence.ts: registry-derived settings, add git provider hydration
- search.ts: upstream search entries + git provider entries
- useConfigStore.ts: loadDesktopSettings() path
- settings-helpers.js: add gitProviderId/gitModelId/gitProviders sanitization
- DOCUMENTATION.md: upstream walkthrough docs
- vite.config.ts: upstream SW glob patterns

Custom fork additions preserved:
- gitProviderId, gitModelId, gitProviders fields in settings registry
- Git provider domain store hydration in persistence.ts
- Git provider search entries in search.ts
- Git provider sanitization in settings-helpers.js

packages/web/index.html

@@ -599,44 +599,6 @@
       }, 10000);
     </script>
 
-    <!-- CSS Font Loading API for reliable Nerd Font loading. The ~2 MB of
-         Nerd Fonts are only used by the terminal viewport, so they are no
-         longer downloaded on every cold start: the terminal requests them on
-         first mount through this idempotent hook. -->
-    <script>
-      (function() {
-        let nerdFontsPromise = null;
-        window.__openchamberEnsureNerdFonts = function() {
-          if (nerdFontsPromise) {
-            return nerdFontsPromise;
-          }
-          const fonts = [
-            {
-              name: 'JetBrainsMono Nerd Font',
-              url: 'https://cdn.jsdelivr.net/gh/mshaugh/nerdfont-webfonts@v3.3.0/build/fonts/JetBrainsMonoNerdFont-Regular.woff2'
-            },
-            {
-              name: 'FiraCode Nerd Font',
-              url: 'https://cdn.jsdelivr.net/gh/mshaugh/nerdfont-webfonts@v3.3.0/build/fonts/FiraCodeNerdFont-Regular.woff2'
-            }
-          ];
-
-          const fontPromises = fonts.map(font => {
-            const fontFace = new FontFace(font.name, `url(${font.url}) format('woff2')`);
-            document.fonts.add(fontFace);
-            return fontFace.load().catch(err => {
-              console.warn(`Failed to load font: ${font.name}`, err);
-            });
-          });
-
-          nerdFontsPromise = Promise.allSettled(fontPromises).then(() => {
-            document.documentElement.classList.add('fonts-loaded');
-          });
-          return nerdFontsPromise;
-        };
-      })();
-    </script>
-
     <!-- Polyfill for process before loading React -->
     <script>
       if (typeof process === 'undefined') {