feat: add URL param for shareable filter state, fix mobile layout

- add hide=... URL param to share links with filters applied
- URL params take precedence over localStorage
- wrap filter + watch live buttons in container that stacks vertically on mobile (<768px)
- adjust filter panel and firehose toast positions for mobile

src/templates/app.html

···
         }
 
         .watch-live-btn {
-            position: fixed;
-            top: clamp(1rem, 2vmin, 1.5rem);
-            right: clamp(1rem, 2vmin, 1.5rem);
             font-family: inherit;
             font-size: clamp(0.65rem, 1.4vmin, 0.75rem);
             color: var(--text-light);
···
             background: var(--bg);
             padding: clamp(0.4rem, 1vmin, 0.5rem) clamp(0.8rem, 2vmin, 1rem);
             transition: all 0.2s ease;
-            z-index: 100;
             cursor: pointer;
             border-radius: 2px;
             display: flex;
···
             animation: pulse 2s ease-in-out infinite;
         }
 
-        .filter-btn {
+        /* Top right button container for filter and watch live */
+        .top-right-buttons {
             position: fixed;
             top: clamp(1rem, 2vmin, 1.5rem);
-            right: clamp(7rem, 14vmin, 10rem);
+            right: clamp(1rem, 2vmin, 1.5rem);
+            display: flex;
+            flex-direction: row;
+            align-items: center;
+            gap: clamp(0.5rem, 1vmin, 0.75rem);
+            z-index: 100;
+        }
+
+        @media (max-width: 768px) {
+            .top-right-buttons {
+                flex-direction: column;
+                align-items: flex-end;
+            }
+        }
+
+        .filter-btn {
             font-family: inherit;
             font-size: clamp(0.65rem, 1.4vmin, 0.75rem);
             color: var(--text-light);
···
             background: var(--bg);
             padding: clamp(0.4rem, 1vmin, 0.5rem) clamp(0.8rem, 2vmin, 1rem);
             transition: all 0.2s ease;
-            z-index: 100;
             cursor: pointer;
             border-radius: 2px;
             display: flex;
···
             max-width: 280px;
             display: none;
             box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
+        }
+
+        @media (max-width: 768px) {
+            .filter-panel {
+                top: clamp(6rem, 12vmin, 8rem);
+            }
         }
 
         @media (prefers-color-scheme: dark) {
···
             pointer-events: none;
             max-width: min(300px, calc(100vw - 2rem));
             width: max-content;
+        }
+
+        @media (max-width: 768px) {
+            .firehose-toast {
+                top: clamp(7rem, 14vmin, 9rem);
+            }
         }
 
         .firehose-toast.visible {
···
             <path d="M12 17h.01" />
         </svg>
     </div>
-    <button class="filter-btn" id="filterBtn">
-        <svg xmlns="http://www.w3.org/2000/svg" width="14" height="14" viewBox="0 0 24 24" fill="none"
-            stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
-            <polygon points="22 3 2 3 10 12.46 10 19 14 21 14 12.46 22 3" />
-        </svg>
-        <span class="filter-label-text">filter</span>
-        <span class="filter-count" id="filterCount" style="display: none;"></span>
-    </button>
+    <div class="top-right-buttons">
+        <button class="filter-btn" id="filterBtn">
+            <svg xmlns="http://www.w3.org/2000/svg" width="14" height="14" viewBox="0 0 24 24" fill="none"
+                stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+                <polygon points="22 3 2 3 10 12.46 10 19 14 21 14 12.46 22 3" />
+            </svg>
+            <span class="filter-label-text">filter</span>
+            <span class="filter-count" id="filterCount" style="display: none;"></span>
+        </button>
+        <button class="watch-live-btn" id="watchLiveBtn">
+            <span class="watch-indicator"></span>
+            <span class="watch-label">watch live</span>
+        </button>
+    </div>
     <div class="filter-panel" id="filterPanel">
         <div class="filter-panel-header">
             <span class="filter-panel-title">show apps</span>
···
         </div>
         <div class="filter-list" id="filterList"></div>
     </div>
-    <button class="watch-live-btn" id="watchLiveBtn">
-        <span class="watch-indicator"></span>
-        <span class="watch-label">watch live</span>
-    </button>
     <div class="pov-indicator">point of view of <a class="pov-handle" id="povHandle" href="#" target="_blank"
             rel="noopener noreferrer"></a></div>
     <div class="guestbook-sign">sign the guest list</div>

static/app.js

···
 // APP FILTER FUNCTIONALITY
 // ============================================================================
 
-// Load hidden apps from localStorage
+// Parse hidden apps from URL param
+function getHiddenAppsFromUrl() {
+    const params = new URLSearchParams(window.location.search);
+    const hideParam = params.get('hide');
+    if (hideParam) {
+        return new Set(hideParam.split(',').filter(Boolean));
+    }
+    return null;
+}
+
+// Update URL with current hidden apps (without page reload)
+function updateUrlWithFilters() {
+    const params = new URLSearchParams(window.location.search);
+    if (hiddenApps.size > 0) {
+        params.set('hide', [...hiddenApps].join(','));
+    } else {
+        params.delete('hide');
+    }
+    const newUrl = params.toString()
+        ? `${window.location.pathname}?${params.toString()}`
+        : window.location.pathname;
+    history.replaceState(null, '', newUrl);
+}
+
+// Load hidden apps from URL param first, then localStorage
 function loadHiddenApps() {
+    // URL takes precedence over localStorage
+    const urlHidden = getHiddenAppsFromUrl();
+    if (urlHidden) {
+        hiddenApps = urlHidden;
+        return;
+    }
+
     try {
         const stored = localStorage.getItem(`atme_hidden_apps_${did}`);
         if (stored) {
···
     }
 }
 
-// Save hidden apps to localStorage
+// Save hidden apps to localStorage and update URL
 function saveHiddenApps() {
     try {
         localStorage.setItem(`atme_hidden_apps_${did}`, JSON.stringify([...hiddenApps]));
     } catch (e) {
         // Silently fail
     }
+    updateUrlWithFilters();
 }
 
 // Update filter button state
···
 
         // After all URL validations complete, apply default "valid" filter (hide unresolved)
         Promise.all(validationPromises).then(() => {
-            // Only apply default if user hasn't set any filters yet
-            if (hiddenApps.size === 0) {
+            // Only apply default if user hasn't set any filters yet AND no URL param was provided
+            const hasUrlFilters = getHiddenAppsFromUrl() !== null;
+            if (hiddenApps.size === 0 && !hasUrlFilters) {
                 // Hide apps with invalid-link class by default
                 const appViews = document.querySelectorAll('.app-view');
                 appViews.forEach(view => {