Add social sharing buttons and QR code for events

Public event page:
- Share buttons: X (Twitter), Facebook, Instagram (copy link), TikTok (copy link), copy link
- Buttons use url_encode for share URLs with event title + URL
- Instagram/TikTok copy to clipboard (no direct share URL support)
- Consistent brutal design with aria-labels

Organizer dashboard:
- Share X, Facebook, copy link buttons per event in events list
- QR code download button per event
- Route /mon-compte/evenement/{id}/qrcode: generates 400px PNG QR code via Endroid
- QR code points to public event URL, downloaded as qrcode-{slug}.png

JS module:
- assets/modules/share.js: initShare() handles data-share-copy buttons
- Copies URL to clipboard, shows checkmark for 1.5s then restores icon
- 4 tests (no buttons, copy, checkmark restore, multiple buttons)

Social icons already displayed via _social_icons.html.twig component

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/js/share.test.js

@@ -0,0 +1,75 @@
+import { describe, it, expect, beforeEach, vi } from 'vitest'
+import { initShare } from '../../assets/modules/share.js'
+
+describe('initShare', () => {
+    beforeEach(() => {
+        document.body.innerHTML = ''
+    })
+
+    it('does nothing without share buttons', () => {
+        expect(() => initShare()).not.toThrow()
+    })
+
+    it('copies URL to clipboard on click', async () => {
+        document.body.innerHTML = `
+            <button data-share-copy="https://example.com/event/1">
+                <svg class="icon"></svg>
+            </button>
+        `
+
+        const writeText = vi.fn().mockResolvedValue(undefined)
+        globalThis.navigator = { clipboard: { writeText } }
+
+        initShare()
+        document.querySelector('[data-share-copy]').click()
+
+        await new Promise(r => setTimeout(r, 10))
+
+        expect(writeText).toHaveBeenCalledWith('https://example.com/event/1')
+    })
+
+    it('shows checkmark after copy then restores', async () => {
+        vi.useFakeTimers()
+
+        document.body.innerHTML = `
+            <button data-share-copy="https://example.com">
+                <svg class="original"></svg>
+            </button>
+        `
+
+        globalThis.navigator = { clipboard: { writeText: vi.fn().mockResolvedValue(undefined) } }
+
+        initShare()
+        const btn = document.querySelector('[data-share-copy]')
+        const originalHtml = btn.innerHTML
+        btn.click()
+
+        await vi.advanceTimersByTimeAsync(100)
+
+        expect(btn.innerHTML).toContain('M5 13l4 4L19 7')
+
+        vi.advanceTimersByTime(1500)
+
+        expect(btn.innerHTML).toBe(originalHtml)
+
+        vi.useRealTimers()
+    })
+
+    it('handles multiple share buttons', async () => {
+        document.body.innerHTML = `
+            <button data-share-copy="https://a.com"><svg></svg></button>
+            <button data-share-copy="https://b.com"><svg></svg></button>
+        `
+
+        const writeText = vi.fn().mockResolvedValue(undefined)
+        globalThis.navigator = { clipboard: { writeText } }
+
+        initShare()
+
+        document.querySelectorAll('[data-share-copy]')[1].click()
+
+        await new Promise(r => setTimeout(r, 10))
+
+        expect(writeText).toHaveBeenCalledWith('https://b.com')
+    })
+})