feat: workspace aliases, tab groups of split panes, native path picker (v2.1.0)

- /api/workspaces and `agenthub workspace(s)` / `--workspace` as aliases of
  /api/lanes and `agenthub lanes` / `--lane`; old names print one stderr note.
  REPL `help lanes|workspace|workspaces` resolves through the aliases.
- A workspace holds up to ten sessions (slots 0-9); every console tab is a
  group of 1-4 split panes (PaneGroups, agenthub.workspace.paneLayout);
  parseGroups keeps the stored active tab when an earlier one is dropped.
- Browse button beside path fields: POST /api/lanes/pick-path opens the OS
  picker on the server's desktop — loopback only and no forwarding header
  (EREMOTE), a display failure is ENODIALOG not a Cancel, the dialog is
  killed when the request closes, a folder field falls back to the in-app
  browser on any failure.
- Changes rail counts chip, image viewer (/git/raw), status bar session
  counts and per-day cost (`date=` on /api/pricing/cost).
- /agenthub-open and /agenthub-doctor run from the INSTALLED build
  (supersededBy), doctor offers fixes behind two confirmations; plugin-open
  treats a locked bootstrap as non-fatal.
- New-terminal shell waits for the first attach (issue #55).
- repo-onboarding / debug-live-issue skills removed.
- OpenAPI: pick-path, lane/date on /pricing/cost, tool on /run/history,
  /api/workspaces mount.

server/lib/worktree.js

@@ -33,7 +33,14 @@ const STATUS_FILE_CAP = 20;
 async function git(
   cwd,
   args,
-  { timeout = 0, maxBuffer = 8 * 1024 * 1024, literal = false, env: extraEnv = {} } = {}
+  {
+    timeout = 0,
+    maxBuffer = 8 * 1024 * 1024,
+    literal = false,
+    env: extraEnv = {},
+    // "buffer" for a binary read (an image at a revision).
+    encoding = "utf8",
+  } = {}
 ) {
   // Build a clean environment: copy process.env but scrub git hook variables
   // that could point to the outer repo's git directory or index.
@@ -79,6 +86,7 @@ async function git(
       // passes one so an unreachable remote fails instead of pinning a request
       // open forever; GIT_TERMINAL_PROMPT=0 only covers the prompting case.
       timeout,
+      encoding,
     });
     return { stdout: result.stdout, stderr: result.stderr };
   } catch (err) {