merge: resolve v1.21.1 conflicts with custom

Resolve all 10 upstream v1.21.1 merge conflicts into custom, keeping
custom's GitLab/Gitea forge customizations layered on upstream while
lifting upstream improvements. Restored tr.ts i18n key parity with the
custom en.ts dictionary (471 custom forge keys added, en fallback) so the
upstream-introduced locale stays in parity.

Also stage bun.lock version alignment (1.21.0 -> 1.21.1) that matches the
staged package.json bump.

Verification: ui + web type-check pass; ui/web tests pass except
pre-existing failures on the custom baseline (forge.test.ts, session-actions,
issue-1637-2270, routes.test.js fs-stat directory scope).

packages/web/server/lib/opencode/settings-helpers.js

@@ -1,3 +1,4 @@
+import { sanitizeGitProviders } from '../git-providers/config.js';
 import { isAgentMemoryFeatureAvailable } from '../agent-memory/feature-flag.js';
 
 export const createSettingsHelpers = (dependencies) => {
@@ -498,6 +499,10 @@ export const createSettingsHelpers = (dependencies) => {
       const trimmed = candidate.gitModelId.trim();
       result.gitModelId = trimmed.length > 0 ? trimmed : undefined;
     }
+    const gitProviders = sanitizeGitProviders(candidate.gitProviders);
+    if (gitProviders) {
+      result.gitProviders = gitProviders;
+    }
     if (typeof candidate.pwaAppName === 'string') {
       result.pwaAppName = normalizePwaAppName(candidate.pwaAppName, undefined);
     }