fix(git): the branch switcher lists and checks out branches only the remote has

GET /api/lanes/:id/git/branches read only refs/heads, so a branch someone
else pushed never showed after a fetch or pull, and `switch` refused it
(ENOBRANCH). It now also returns `remotes`: fetched remote-tracking branches
with no local branch of that name (origin/HEAD left out), listed under
"On the remote"; switching to one runs `git switch -c <b> --track
refs/remotes/<remote>/<b>` with the remote ref looked up, never passed
through (bare name only when exactly one remote has it, else EAMBIGUOUS).
The bar also re-reads the branch list after a fetch or pull instead of
keeping the list it loaded first.

client/src/i18n/locales/en/lanes.json

@@ -195,6 +195,7 @@
   "gitBar.switch": "Branch",
   "gitBar.switchApply": "Switch branch",
   "gitBar.switchCurrent": "current",
+  "gitBar.remoteBranches": "On the remote — switching creates the local branch",
   "gitBar.switchDirty": "Commit or discard the uncommitted changes first",
   "gitBar.switchHint": "Switch this worktree to another local branch",
   "gitBar.switchLabel": "Switch branch…",

client/src/i18n/locales/vi/lanes.json

@@ -195,6 +195,7 @@
   "gitBar.switch": "Nhánh",
   "gitBar.switchApply": "Chuyển nhánh",
   "gitBar.switchCurrent": "hiện tại",
+  "gitBar.remoteBranches": "Trên remote — switch sẽ tạo nhánh local",
   "gitBar.switchDirty": "Hãy commit hoặc bỏ các thay đổi chưa commit trước",
   "gitBar.switchHint": "Đổi worktree này sang nhánh local khác",
   "gitBar.switchLabel": "Đổi nhánh…",