feat: Implement TagSelector component for event tagging (closes #371)

- Add TagSelector component with full keyboard support:
  * Enter/Comma to add tags
  * Backspace to remove last tag
  * Arrow keys to navigate autocomplete suggestions
  * Escape to close suggestions

- Prevent duplicate tags (case-insensitive)
- Max 10 tags per event, 20 characters per tag
- Autocomplete suggestions with 6-item dropdown
- Integrate into CreateEventForm with validation

- Update event schema to include tags field with zod validation
- Add fallback error handling with inline TailwindCSS styling
- Storybook stories and unit tests included
- All acceptance criteria met: add/remove, keyboard support, duplicates, autocomplete

Author: dDevAhmed

app/frontend/components/forms/CreateEventForm.tsx

@@ -5,6 +5,22 @@ import { zodResolver } from '@hookform/resolvers/zod';
 import { z } from 'zod';
 import FormInput from './FormInput';
 import ErrorSummary from './ErrorSummary';
+import { TagSelector } from '@/components/ui/atoms';
+
+const TAG_SUGGESTIONS = [
+  'Web3',
+  'Blockchain',
+  'Stellar',
+  'Soroban',
+  'Hackathon',
+  'Workshop',
+  'Networking',
+  'Startup',
+  'AI',
+  'DeFi',
+  'Community',
+  'Technology',
+];
 
 // ─── Schema ───────────────────────────────────────────────────────────────────
 const createEventSchema = z.object({
@@ -29,6 +45,12 @@ const createEventSchema = z.object({
   category: z.enum(['conference', 'workshop', 'concert', 'hackathon', 'meetup', ''], {
     errorMap: () => ({ message: 'Please select a category' }),
   }).refine(v => v !== '', { message: 'Please select a category' }),
+  tags: z
+    .array(z.string().trim().min(1).max(20, 'Tag cannot exceed 20 characters'))
+    .max(10, 'You can add up to 10 tags')
+    .refine((tags) => new Set(tags.map((tag) => tag.toLowerCase())).size === tags.length, {
+      message: 'Duplicate tags are not allowed',
+    }),
   isPublic: z.boolean(),
   websiteUrl: z
     .string()
@@ -46,6 +68,7 @@ const FIELD_LABELS: Record<string, string> = {
   ticketPrice: 'Ticket Price',
   maxAttendees: 'Max Attendees',
   category: 'Category',
+  tags: 'Tags',
   isPublic: 'Visibility',
   websiteUrl: 'Website URL',
 };
@@ -101,6 +124,7 @@ export default function CreateEventForm() {
       ticketPrice: '0',
       maxAttendees: '100',
       category: '',
+      tags: [],
       isPublic: true,
       websiteUrl: '',
     },
@@ -193,6 +217,23 @@ export default function CreateEventForm() {
         <option value="meetup">Meetup</option>
       </FormInput>
 
+      {/* Tags */}
+      <Controller
+        name="tags"
+        control={control}
+        render={({ field }) => (
+          <TagSelector
+            label="Tags"
+            name={field.name}
+            value={field.value}
+            onChange={field.onChange}
+            suggestions={TAG_SUGGESTIONS}
+            hint="Press Enter or comma to add tags. Backspace removes the last tag."
+            error={errors.tags}
+          />
+        )}
+      />
+
       {/* Price + Attendees side by side */}
       <div className="grid grid-cols-2 gap-4">
         <FormInput
@@ -268,7 +309,7 @@ export default function CreateEventForm() {
               role="switch"
               aria-checked={field.value}
               onClick={() => field.onChange(!field.value)}
-              className={`relative w-11 h-6 rounded-full transition-all duration-200 flex-shrink-0 ${
+              className={`relative w-11 h-6 rounded-full transition-all duration-200 shrink-0 ${
                 field.value ? 'bg-[#3d5afe]' : 'bg-[#1e2333]'
               }`}
             >

app/frontend/components/forms/schema/eventSchema.ts

@@ -47,6 +47,13 @@ export const createEventSchema = z.object({
 
   websiteUrl: z.string().optional().or(z.literal('')),
 
+  tags: z
+    .array(z.string().trim().min(1, 'Tags cannot be empty').max(20, 'Tag cannot exceed 20 characters'))
+    .max(10, 'You can add up to 10 tags')
+    .refine((tags) => new Set(tags.map((tag) => tag.toLowerCase())).size === tags.length, {
+      message: 'Tags must be unique',
+    }),
+
   isPublic: z.boolean().default(true),
 });
 
@@ -61,6 +68,7 @@ export const EVENT_FIELD_LABELS: Record<string, string> = {
   maxAttendees: 'Max Attendees',
   contractAddress: 'Contract Address',
   websiteUrl: 'Website URL',
+  tags: 'Tags',
   isPublic: 'Visibility',
 };
 
@@ -73,5 +81,6 @@ export const createEventDefaults: CreateEventFormValues = {
   maxAttendees: '100',
   contractAddress: '',
   websiteUrl: '',
+  tags: [],
   isPublic: true,
 };

app/frontend/components/ui/atoms/TagSelector/TagSelector.stories.tsx

@@ -0,0 +1,65 @@
+import type { Meta, StoryObj } from '@storybook/react';
+import { useState } from 'react';
+import { TagSelector } from './TagSelector';
+
+const meta: Meta<typeof TagSelector> = {
+  title: 'UI/Atoms/TagSelector',
+  component: TagSelector,
+  tags: ['autodocs'],
+};
+
+export default meta;
+type Story = StoryObj<typeof meta>;
+
+const DEFAULT_SUGGESTIONS = [
+  'Web3',
+  'Stellar',
+  'Hackathon',
+  'Networking',
+  'Workshop',
+  'Community',
+  'Technology',
+  'Startup',
+];
+
+export const Default: Story = {
+  render: (args) => {
+    const [tags, setTags] = useState<string[]>(['Stellar']);
+
+    return (
+      <div className="w-[520px]">
+        <TagSelector
+          {...args}
+          value={tags}
+          onChange={setTags}
+        />
+      </div>
+    );
+  },
+  args: {
+    label: 'Event Tags',
+    suggestions: DEFAULT_SUGGESTIONS,
+    hint: 'Press Enter to add. Use Backspace to remove the last tag.',
+  },
+};
+
+export const WithError: Story = {
+  render: (args) => {
+    const [tags, setTags] = useState<string[]>([]);
+
+    return (
+      <div className="w-[520px]">
+        <TagSelector
+          {...args}
+          value={tags}
+          onChange={setTags}
+          error={{ message: 'At least one tag is required' }}
+        />
+      </div>
+    );
+  },
+  args: {
+    label: 'Event Tags',
+    suggestions: DEFAULT_SUGGESTIONS,
+  },
+};

app/frontend/components/ui/atoms/TagSelector/TagSelector.test.tsx

@@ -0,0 +1,59 @@
+import { describe, it, expect, vi } from 'vitest';
+import { render, screen, fireEvent } from '@testing-library/react';
+import { TagSelector } from './TagSelector';
+
+describe('TagSelector', () => {
+  it('adds tags with Enter key', () => {
+    const onChange = vi.fn();
+    render(<TagSelector label="Tags" value={[]} onChange={onChange} />);
+
+    const input = screen.getByLabelText('Tags');
+    fireEvent.change(input, { target: { value: 'Stellar' } });
+    fireEvent.keyDown(input, { key: 'Enter' });
+
+    expect(onChange).toHaveBeenCalledWith(['Stellar']);
+  });
+
+  it('prevents duplicate tags', () => {
+    const onChange = vi.fn();
+    render(<TagSelector label="Tags" value={['Stellar']} onChange={onChange} />);
+
+    const input = screen.getByLabelText('Tags');
+    fireEvent.change(input, { target: { value: 'stellar' } });
+    fireEvent.keyDown(input, { key: 'Enter' });
+
+    expect(onChange).not.toHaveBeenCalled();
+    expect(screen.getByText('Tag already added')).toBeInTheDocument();
+  });
+
+  it('removes last tag on Backspace when input is empty', () => {
+    const onChange = vi.fn();
+    render(<TagSelector label="Tags" value={['Web3', 'Stellar']} onChange={onChange} />);
+
+    const input = screen.getByLabelText('Tags');
+    fireEvent.keyDown(input, { key: 'Backspace' });
+
+    expect(onChange).toHaveBeenCalledWith(['Web3']);
+  });
+
+  it('shows suggestions and allows selecting one', () => {
+    const onChange = vi.fn();
+    render(
+      <TagSelector
+        label="Tags"
+        value={[]}
+        onChange={onChange}
+        suggestions={['Hackathon', 'Workshop']}
+      />
+    );
+
+    const input = screen.getByLabelText('Tags');
+    fireEvent.focus(input);
+    fireEvent.change(input, { target: { value: 'work' } });
+
+    const suggestion = screen.getByRole('option', { name: 'Workshop' });
+    fireEvent.mouseDown(suggestion);
+
+    expect(onChange).toHaveBeenCalledWith(['Workshop']);
+  });
+});