refactor: move supporters loading to separate API endpoint

- Add SupportersHandler in misc_handlers.py to serve /api/lm/supporters
- Register new endpoint in misc_route_registrar.py
- Remove supporters from page load template context in model_handlers.py
- Create supportersService.js for frontend data fetching
- Update Header.js to fetch supporters when support modal opens
- Modify support_modal.html to use client-side rendering

This change improves page load performance by loading supporters data
on-demand instead of during initial page render.

static/js/services/supportersService.js

@@ -0,0 +1,104 @@
+/**
+ * Supporters service - Fetches and manages supporters data
+ */
+
+let supportersData = null;
+let isLoading = false;
+let loadPromise = null;
+
+/**
+ * Fetch supporters data from the API
+ * @returns {Promise<Object>} Supporters data
+ */
+export async function fetchSupporters() {
+    // Return cached data if available
+    if (supportersData) {
+        return supportersData;
+    }
+
+    // Return existing promise if already loading
+    if (isLoading && loadPromise) {
+        return loadPromise;
+    }
+
+    isLoading = true;
+    loadPromise = fetch('/api/lm/supporters')
+        .then(response => {
+            if (!response.ok) {
+                throw new Error(`Failed to fetch supporters: ${response.statusText}`);
+            }
+            return response.json();
+        })
+        .then(data => {
+            if (data.success && data.supporters) {
+                supportersData = data.supporters;
+                return supportersData;
+            }
+            throw new Error(data.error || 'Failed to load supporters data');
+        })
+        .catch(error => {
+            console.error('Error loading supporters:', error);
+            // Return empty data on error
+            return {
+                specialThanks: [],
+                allSupporters: [],
+                totalCount: 0
+            };
+        })
+        .finally(() => {
+            isLoading = false;
+            loadPromise = null;
+        });
+
+    return loadPromise;
+}
+
+/**
+ * Clear cached supporters data
+ */
+export function clearSupportersCache() {
+    supportersData = null;
+}
+
+/**
+ * Render supporters in the support modal
+ */
+export async function renderSupporters() {
+    const supporters = await fetchSupporters();
+
+    // Update subtitle with total count
+    const subtitleEl = document.getElementById('supportersSubtitle');
+    if (subtitleEl) {
+        // Get the translation key and replace count
+        const originalText = subtitleEl.textContent;
+        // Replace the count in the text (simple approach)
+        subtitleEl.textContent = originalText.replace(/\d+/, supporters.totalCount);
+    }
+
+    // Render special thanks
+    const specialThanksGrid = document.getElementById('specialThanksGrid');
+    if (specialThanksGrid && supporters.specialThanks) {
+        specialThanksGrid.innerHTML = supporters.specialThanks
+            .map(supporter => `
+                <div class="supporter-special-card" title="${supporter}">
+                    <span class="supporter-special-name">${supporter}</span>
+                </div>
+            `)
+            .join('');
+    }
+
+    // Render all supporters
+    const supportersGrid = document.getElementById('supportersGrid');
+    if (supportersGrid && supporters.allSupporters) {
+        supportersGrid.innerHTML = supporters.allSupporters
+            .map((supporter, index, array) => {
+                const separator = index < array.length - 1
+                    ? '<span class="supporter-separator">·</span>'
+                    : '';
+                return `
+                    <span class="supporter-name-item" title="${supporter}">${supporter}</span>${separator}
+                `;
+            })
+            .join('');
+    }
+}