Add plugin platform with modular backend and frontend registry.

Split graph/import/meta into Django apps, add API v1 with OpenAPI and pytest, and introduce plugin registry with the tags reference plugin on both FE and BE.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/views/GraphView.vue

@@ -21,6 +21,17 @@
         :active-values="activeFilters"
         @toggle="toggleFilter"
       />
+      <div v-if="graphToolbarActions.length" class="graph-plugin-actions">
+        <button
+          v-for="action in graphToolbarActions"
+          :key="action.id"
+          type="button"
+          class="btn btn-secondary btn-sm"
+          @click="runGraphToolbarAction(action)"
+        >
+          {{ action.label }}
+        </button>
+      </div>
     </div>
 
     <div class="graph-area" ref="graphArea">
@@ -150,7 +161,7 @@
 defineOptions({ name: 'Graph' })
 
 import { ref, computed, onMounted, onUnmounted, onActivated, onDeactivated, nextTick, watch } from 'vue'
-import { RouterLink } from 'vue-router'
+import { RouterLink, useRouter } from 'vue-router'
 import { Network, DataSet } from 'vis-network/standalone'
 import { useContactsStore } from '../stores/contacts'
 import { useCtrlLinkSelection } from '../composables/useCtrlLinkSelection'
@@ -168,6 +179,7 @@ import GraphNodeContextMenu from '../components/GraphNodeContextMenu.vue'
 import GraphEdgeContextMenu from '../components/GraphEdgeContextMenu.vue'
 import EditRelationModal from '../components/EditRelationModal.vue'
 import { useGraphNodeContextMenu } from '../composables/useGraphNodeContextMenu.js'
+import { getGraphToolbarActions } from '../core/pluginRegistry'
 
 let themeObserver = null
 let detachContextHandler = null
@@ -191,6 +203,8 @@ function openNodeInfo(node) {
 }
 
 const store = useContactsStore()
+const router = useRouter()
+const graphToolbarActions = getGraphToolbarActions()
 const graphArea = ref(null)
 const graphContainer = ref(null)
 const loading = ref(true)
@@ -774,6 +788,10 @@ function toggleChrome() {
   nextTick(() => network.value?.redraw())
 }
 
+function runGraphToolbarAction(action) {
+  action.onClick?.({ router })
+}
+
 watch(() => store.dataRevision, async (revision) => {
   if (!network.value || revision === syncedRevision) return
   await applyGraphDataFromStore()
@@ -832,6 +850,11 @@ onUnmounted(() => {
   flex-shrink: 0;
   padding: 0 28px 10px;
 }
+.graph-plugin-actions {
+  display: flex;
+  gap: 8px;
+  margin-top: 8px;
+}
 .graph-chrome-bar {
   display: flex;
   justify-content: center;