Give the mouse back, retire the follow controls, update Claude per session

Three things the terminal was getting wrong.

**A program that grabs the mouse and dies used to freeze the tab.** A TUI sets
DECSET ?1000/?1002/?1003; if it exits without resetting them, xterm keeps
routing clicks, drags and — under ?1003 — every pointer *move* to the PTY.
Text selection dies and escape bytes flood the prompt. The only exit was
closing the tab. `TerminalView` now reconciles a flag against
`term.modes.mouseTrackingMode` in the `term.write()` callback — the mode only
changes because the container printed a sequence, so one check per write
catches every transition with no polling — and `Ctrl+Shift+X` or a status-bar
button writes the resets back through `term.write`, never `sendInput`: the
reset belongs to xterm's parser, and a still-live TUI told about it would just
re-grab on its next repaint.

The control is in the status bar deliberately. Mouse tracking is the *normal*
state of htop, vim, lazygit and Claude Code, so a badge over the terminal
would be on screen for the whole life of those programs and would swallow
clicks aimed at their own top-right corner. `macOptionClickForcesSelection` is
also on now: xterm's force-select is Shift everywhere except macOS, where it
is Option and is gated behind that option, which defaults to false — so until
now Mac users had no way to select text while a program held the mouse.

**"Following" and "Jump to Current" are gone.** Claude Code draws on the
alternate screen, which has no scrollback, so `viewportY` always equalled
`baseY` and neither control could do anything. They did still work in bash
tabs; xterm's native follow covers that, and the per-write `scrollToBottom()`
went with them because it fought exactly that. What remains, on activate and
after a refit, now samples `viewportY >= baseY` *before* the fit, so opening
the Notes dock no longer yanks a reader to the tail.

**`claude update` runs before every Claude session, not just at container
start.** Containers here stop/start and often just keep running, so a
long-lived one never re-checked. Both copies take the same flock: the
entrypoint prints "container ready" only after its own update finishes, so
opening a tab immediately would otherwise run two updaters against the same
~/.claude/bin, with `|| echo` hiding a half-written install one line before
`exec claude` ran it.

This turns the non-Bedrock path from a bare argv into a `bash -c` wrapper, so
flags and session names are shell-interpolated now and must go through
`shell_quote_arg`.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0145mQi9NZiCDrznBUEEDE4n

app/src/lib/dropTarget.test.ts

@@ -243,11 +243,12 @@ describe("dropTarget", () => {
   describe("chrome over a pane, with no dialog open", () => {
     /** Everything that is painted over a pane and is not a blocker. */
     const CHROME: Array<[string, () => HTMLElement]> = [
-      // `TerminalView`'s "▼ Following / ▽ Paused" toggle: `absolute top-2
-      // right-4 z-50`, rendered unconditionally, and a *sibling* of the xterm
-      // host — so "does the pane contain what is painted here?" made the
-      // terminal's top-right corner a dead zone no user action could clear.
-      ["the Following/Paused toggle", () => document.createElement("button")],
+      // `TerminalView`'s mouse-release badge: `absolute top-2 right-4 z-50`,
+      // and a *sibling* of the xterm host — so "does the pane contain what is
+      // painted here?" made the terminal's top-right corner a dead zone no
+      // user action could clear. (The retired Following toggle held the same
+      // corner and produced the original bug.)
+      ["the mouse-release badge", () => document.createElement("button")],
       // `ToastHost`: `fixed bottom-4 right-4 z-[60]`, 24rem wide, over every
       // pane, and its error cards stay until dismissed.
       ["a toast card", () => document.createElement("div")],

app/src/lib/dropTarget.ts

@@ -26,8 +26,8 @@
  *
  * - Asking `el.contains(document.elementFromPoint(x, y))` — "is the thing
  *   painted here mine?" — refused drops onto anything painted *over* a pane
- *   that is not part of it: `TerminalView`'s always-rendered "▼ Following"
- *   toggle (a sibling of the xterm host), the URL toast, `ToastHost`'s stack.
+ *   that is not part of it: `TerminalView`'s mouse-release badge (a sibling
+ *   of the xterm host), the URL toast, `ToastHost`'s stack.
  *   Permanent dead zones no user action could clear.
  * - Replacing that with "is a *blocking overlay* painted here?" removed the
  *   dead zones and opened a hole instead. `elementFromPoint` returns the