feat(frontend): Phase 5c-v — custom-geo section in VersionModal

Adds the third collapse panel ("Custom geo") that lets users register
external geosite/geoip files referenced by routing rules via
ext:<filename>:tag. Backend endpoints are unchanged.

- CustomGeoSection.vue: bordered table over /panel/api/custom-geo/list
  with per-row edit, download (refetch), and delete actions, plus an
  Add button and Update-all. Lazy-loads the list when the parent
  collapse opens this panel — closed panels don't fetch.
- CustomGeoFormModal.vue: shared add/edit form with the same alias
  regex (^[a-z0-9_-]+$) and URL validation as legacy. Type and alias
  are immutable when editing — backend rejects changes anyway.
- ext:<filename>:tag value is click-to-copy via ClipboardManager.
- Relative time is computed inline (no moment dep); tooltip shows the
  absolute timestamp.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

frontend/src/pages/index/CustomGeoFormModal.vue

@@ -0,0 +1,112 @@
+<script setup>
+import { reactive, ref, watch } from 'vue';
+import { message } from 'ant-design-vue';
+import { HttpUtil } from '@/utils';
+
+const props = defineProps({
+  open: { type: Boolean, default: false },
+  // Populate with the record when editing; null/undefined when adding.
+  record: { type: Object, default: null },
+});
+
+const emit = defineEmits(['update:open', 'saved']);
+
+const form = reactive({ type: 'geosite', alias: '', url: '' });
+const saving = ref(false);
+
+const editing = ref(false);
+const editId = ref(null);
+
+watch(() => props.open, (next) => {
+  if (!next) return;
+  if (props.record) {
+    editing.value = true;
+    editId.value = props.record.id;
+    form.type = props.record.type;
+    form.alias = props.record.alias;
+    form.url = props.record.url;
+  } else {
+    editing.value = false;
+    editId.value = null;
+    form.type = 'geosite';
+    form.alias = '';
+    form.url = '';
+  }
+});
+
+function close() {
+  emit('update:open', false);
+}
+
+function validate() {
+  // Backend expects a filesystem-safe alias; legacy enforces the same regex.
+  if (!/^[a-z0-9_-]+$/.test(form.alias || '')) {
+    message.error('Alias must contain only lowercase letters, digits, dashes or underscores.');
+    return false;
+  }
+  const u = (form.url || '').trim();
+  if (!/^https?:\/\//i.test(u)) {
+    message.error('URL must start with http:// or https://');
+    return false;
+  }
+  try {
+    const parsed = new URL(u);
+    if (parsed.protocol !== 'http:' && parsed.protocol !== 'https:') {
+      message.error('URL must start with http:// or https://');
+      return false;
+    }
+  } catch (_e) {
+    message.error('URL must start with http:// or https://');
+    return false;
+  }
+  return true;
+}
+
+async function submit() {
+  if (!validate()) return;
+  saving.value = true;
+  try {
+    const url = editing.value
+      ? `/panel/api/custom-geo/update/${editId.value}`
+      : '/panel/api/custom-geo/add';
+    const msg = await HttpUtil.post(url, form);
+    if (msg?.success) {
+      emit('saved');
+      close();
+    }
+  } finally {
+    saving.value = false;
+  }
+}
+</script>
+
+<template>
+  <a-modal
+    :open="open"
+    :title="editing ? 'Edit custom geo entry' : 'Add custom geo entry'"
+    :confirm-loading="saving"
+    ok-text="Save"
+    cancel-text="Close"
+    @ok="submit"
+    @cancel="close"
+  >
+    <a-form layout="vertical">
+      <a-form-item label="Type">
+        <a-select v-model:value="form.type" :disabled="editing">
+          <a-select-option value="geosite">geosite</a-select-option>
+          <a-select-option value="geoip">geoip</a-select-option>
+        </a-select>
+      </a-form-item>
+      <a-form-item label="Alias">
+        <a-input
+          v-model:value="form.alias"
+          :disabled="editing"
+          placeholder="lowercase letters, digits, dashes, underscores"
+        />
+      </a-form-item>
+      <a-form-item label="URL">
+        <a-input v-model:value="form.url" placeholder="https://" />
+      </a-form-item>
+    </a-form>
+  </a-modal>
+</template>