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/fs/routes.js

@@ -800,6 +800,14 @@ export const registerFsRoutes = (app, dependencies) => {
         openchamberUserConfigRoot,
       });
       if (!resolved.ok) {
+        // An `optional` stat is a graceful probe — the caller only wants to
+        // know whether a path resolves to a readable file, and treats both
+        // "missing" and "outside the active workspace" as absent. Without this,
+        // boot-time probes of config/backup paths outside the workspace 400 and
+        // surface as console errors for a check that was never mandatory.
+        if (optional && resolved.error === 'Path is outside of active workspace') {
+          return res.json({ path: filePath, exists: false });
+        }
         if (req.query?.allowOutsideWorkspace === 'true') {
           console.warn(`Rejected outside-workspace stat: ${resolved.error}`);
         }