fix: resolve Live catalog projection failure during Analyze again in Laya mode (#17)

Fix the regression introduced by the weighted Laya signal (#16):
rebuild now merges exact fingerprints in every engine mode after
evaluating hard blockers, compares candidates against all variants
of a group, falls back to deterministic scoring when Laya is
unavailable, and reports transaction errors safely. Non-regression
tests cover the Laya-mode rebuild path; verified against a real
catalog copy (39,341 streams rebuilt successfully).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

test/liveGroupingScoring.test.js

@@ -7,6 +7,7 @@ const {
 } = require('../server/services/liveGroupingScoring');
 const {
     collectIdentityHints,
+    collectOptionalIdentityHints,
     normalizeChannelName,
     projectCatalog
 } = require('../server/services/liveProjectionService');
@@ -44,6 +45,16 @@ test('exact algorithm match survives a contradictory Laya opinion', () => {
     assert.equal(score.signals.laya, 0);
 });
 
+test('exact generic fingerprints merge in Laya-only mode without family metadata', () => {
+    const left = channel('a', '1000 x Hora TV', { category_id: 'one' });
+    const right = channel('b', '|UY| 1000 x Hora TV', { category_id: 'two' });
+    const score = scoreCandidate(left, right, { mode: 'laya' });
+    assert.equal(score.total, 55);
+    assert.equal(score.matched, true);
+    const groups = projectCatalog([left, right], { mode: 'laya' });
+    assert.equal(groups.length, 1);
+});
+
 test('different channel numbers block even when Laya proposes a merge', () => {
     const left = channel('a', 'beIN Sports 1');
     const right = channel('b', 'beIN Sports 2');
@@ -110,3 +121,28 @@ test('hybrid mode caps the positive Laya contribution at weight 10', () => {
     assert.equal(score.total, 72);
     assert.equal(score.matched, true);
 });
+
+test('Laya bridge followed by an exact alias stays in one unique fingerprint group', () => {
+    const items = [
+        channel('a', 'beIN Sports 1 Event'),
+        channel('b', 'beIN Sports 1'),
+        channel('c', 'beIN Sports 1')
+    ];
+    const hints = new Map([[
+        ['a', 'b'].sort().join('\0'),
+        { sameIdentityProbability: 1, confidence: 1 }
+    ]]);
+    const groups = projectCatalog(items, { mode: 'hybrid', identityHints: hints });
+    assert.equal(groups.length, 1);
+    assert.equal(groups[0].fingerprint, 'bein sports 1');
+    assert.equal(groups[0].variants.length, 3);
+});
+
+test('optional Laya failure degrades to an empty signal set', async () => {
+    const hints = await collectOptionalIdentityHints([
+        channel('a', 'beIN Sports 1 Event'), channel('b', 'beIN Sports 1')
+    ], 'hybrid', {
+        identityHintBatch: async () => { throw new Error('runtime unavailable at https://private.invalid'); }
+    });
+    assert.equal(hints.size, 0);
+});