feat: add sidebar view with form list

ItemView that displays all forms with mode badges (C/U), click to open,
settings gear button, and empty state. Uses SidebarPluginRef interface
to avoid circular dependency with main.ts.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/ui/form-sidebar.ts

@@ -0,0 +1,94 @@
+import { ItemView, WorkspaceLeaf, setIcon } from 'obsidian';
+import { FormStore } from '../core/form-store';
+
+export const VIEW_TYPE_FORMFIRE_SIDEBAR = 'formfire-sidebar';
+
+/**
+ * Interface for the subset of FormfirePlugin that the sidebar needs.
+ * Avoids circular dependency with main.ts.
+ */
+export interface SidebarPluginRef {
+  store: FormStore;
+  openForm: (id: string) => void;
+}
+
+export class FormfireSidebarView extends ItemView {
+  private pluginRef: SidebarPluginRef;
+
+  constructor(leaf: WorkspaceLeaf, pluginRef: SidebarPluginRef) {
+    super(leaf);
+    this.pluginRef = pluginRef;
+  }
+
+  getViewType(): string {
+    return VIEW_TYPE_FORMFIRE_SIDEBAR;
+  }
+
+  getDisplayText(): string {
+    return 'Formfire';
+  }
+
+  getIcon(): string {
+    return 'file-input';
+  }
+
+  async onOpen(): Promise<void> {
+    this.render();
+  }
+
+  async onClose(): Promise<void> {
+    this.contentEl.empty();
+  }
+
+  public render(): void {
+    const { contentEl } = this;
+    contentEl.empty();
+
+    const container = contentEl.createDiv({ cls: 'ff-sidebar' });
+
+    // Header
+    const header = container.createDiv({ cls: 'ff-sidebar-header' });
+    header.createSpan({ text: 'Forms', cls: 'ff-sidebar-title' });
+
+    const settingsBtn = header.createDiv({ cls: 'ff-sidebar-settings' });
+    setIcon(settingsBtn, 'settings');
+    settingsBtn.setAttribute('aria-label', 'Formfire settings');
+    settingsBtn.addEventListener('click', () => {
+      // Open Obsidian settings and navigate to the Formfire tab
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      const appAny = this.app as any;
+      appAny.setting.open();
+      appAny.setting.openTabById('formfire');
+    });
+
+    // Form list
+    const forms = this.pluginRef.store.getAll();
+
+    if (forms.length === 0) {
+      container.createDiv({
+        cls: 'ff-sidebar-empty',
+        text: 'No forms yet. Open settings to create one.',
+      });
+      return;
+    }
+
+    const listEl = container.createDiv({ cls: 'ff-sidebar-list' });
+
+    for (const form of forms) {
+      const item = listEl.createDiv({ cls: 'ff-sidebar-item' });
+
+      const badgeCls =
+        form.mode === 'create' ? 'ff-badge-create' : 'ff-badge-update';
+      item.createSpan({
+        cls: `ff-sidebar-badge ${badgeCls}`,
+        text: form.mode === 'create' ? 'C' : 'U',
+      });
+
+      item.createSpan({ cls: 'ff-sidebar-name', text: form.name });
+
+      item.addEventListener('click', () => {
+        this.pluginRef.openForm(form.id);
+      });
+    }
+  }
+}