v3 : vote par la chaîne, corrections de la relecture de 74f96be (interface)

- rien n'est parti (nœud muet avant la signature, refus, fenêtre fermée avant) :
  la page lâche le bulletin ; signé, ou montré en code Ğecko, il est gardé et
  le serveur le confirme sans la page ; le refus de la chaîne se dit (« chain ») ;
- le reçu : téléchargeable depuis la fenêtre de vote, et la page « Tes
  bulletins » (/bulletins) qui garde l'historique et vérifie un reçu dans le
  navigateur, sans le serveur (lib/receipt.ts, mêmes vecteurs que le moteur) ;
- le panier ne dit plus « Tes votes comptent dès l'envoi » quand le vote est fermé ;
- @noble/hashes déclaré (utilisé par e2e/chain-mock.mjs et le reçu) ;
- chaîne simulée : finalité, pages, filtres, nœud qui tombe ; contrôles C32, C33.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/tests/unit/receipt.test.ts

@@ -0,0 +1,73 @@
+// The receipt of a vote on the Ğ1 chain, checked in the browser: the same
+// canonical text and the same seal as the engine (crates/ld-engine/src/ballot.rs,
+// whose vectors were computed apart with Python's hashlib.blake2b).
+import { describe, expect, it } from 'vitest';
+import { canonical, checkReceipt, seal } from '../../src/lib/receipt';
+
+const SALT = '00112233445566778899aabbccddeeff';
+const LINES = [
+  { proposalId: 'p2', revision: 1, choice: 'against' as const },
+  { proposalId: 'p1', revision: 3, choice: 'for' as const },
+];
+
+describe('the sealed ballot', () => {
+  it('reads as the engine writes it, the lines in the order of their versions', () => {
+    expect(canonical('d0c', null, LINES, SALT)).toBe(
+      'ld1\ndoc d0c\nauthor -\nline p1 3 for\nline p2 1 against\nsalt 00112233445566778899aabbccddeeff\n',
+    );
+  });
+
+  it('seals to the remark of the engine', () => {
+    const s = seal('d0c', null, LINES, SALT);
+    expect(s?.digest).toBe('20448d496744292981c8586856afb58a86e37da2470f764b4e6ed84eade71340');
+    expect(s?.comment).toBe('ld1:20448d496744292981c8586856afb58a86e37da2470f764b4e6ed84eade71340');
+    expect(s?.remarkHash).toBe('0xe765221a75716dde863a7b53df3a97acf6db38a2118edd525d54c8a2979b7bc3');
+    const bound = seal('d0c', 'g1NrqKgJW9FoFabaYW82zhS9tDWdQcL1DGpivaJdj7GW9M6iv', [{ proposalId: 'p1', revision: 3, choice: 'none' }], 'ffeeddccbbaa99887766554433221100');
+    expect(bound?.digest).toBe('6a6d8a90b5003ff3c4d050dbd36199e8bbf34c4cc11620618399226c9237c05e');
+    expect(bound?.remarkHash).toBe('0x846495fe62b9a5184a0d3090d4d26f621887c334890404169c00575ee74540e4');
+  });
+
+  it('what cannot be sealed', () => {
+    expect(seal('d0c', null, [], SALT)).toBeNull();
+    expect(seal('d0c', null, [LINES[0]!, { ...LINES[0]!, revision: 2 }], SALT)).toBeNull();
+    expect(seal('d 0c', null, LINES, SALT)).toBeNull();
+    expect(seal('d0c', null, LINES, SALT.toUpperCase())).toBeNull();
+    expect(seal('d0c', null, LINES, '0011')).toBeNull();
+    expect(seal('d0c', null, [{ proposalId: 'p1', revision: 1.5, choice: 'for' }], SALT)).toBeNull();
+  });
+});
+
+describe('a receipt', () => {
+  const receipt = {
+    format: 'ld1',
+    doc: 'd0c',
+    author: null,
+    lines: LINES.map((l) => ({ ...l, article: 'E1', title: 'Unicité du compte' })),
+    salt: SALT,
+    comment: 'ld1:20448d496744292981c8586856afb58a86e37da2470f764b4e6ed84eade71340',
+    block: 3_400_000,
+  };
+
+  it('holds when its lines and its salt give its comment', () => {
+    expect(checkReceipt(JSON.stringify(receipt))).toEqual({
+      kind: 'ok',
+      comment: receipt.comment,
+      remarkHash: '0xe765221a75716dde863a7b53df3a97acf6db38a2118edd525d54c8a2979b7bc3',
+      block: 3_400_000,
+      lines: receipt.lines,
+    });
+  });
+
+  it('does not hold once a choice is changed', () => {
+    const changed = { ...receipt, lines: [{ ...receipt.lines[0]!, choice: 'for' }, receipt.lines[1]!] };
+    const check = checkReceipt(JSON.stringify(changed));
+    expect(check.kind).toBe('mismatch');
+    if (check.kind === 'mismatch') expect(check.computed).not.toBe(receipt.comment);
+  });
+
+  it('what is not a receipt', () => {
+    for (const text of ['', 'nope', '[]', '{}', JSON.stringify({ ...receipt, format: 'ld2' }), JSON.stringify({ ...receipt, lines: 'x' })]) {
+      expect(checkReceipt(text).kind, text).toBe('unreadable');
+    }
+  });
+});