fix(terminal): let a detached session's own window own its pane size

Popping a session out left both windows sizing the same pane. The dashboard
keeps the session active and keeps measuring it, and its terminal is
narrower than the popup because the session rail takes width the popup does
not have. One PTY cannot hold two sizes, so the CLI drew frames that fit
neither window and the popup showed a garbled frame.

sendResize and the debounced window-resize handler now stand aside for a
session this window has marked detached. A solo window is exempt, since it
is the owner. _maybeRefetchFullHistory already stood aside on exactly this
condition, so the rule is not a new one.

Sizing has to come back when the popup closes: while it owned the session
the dashboard sent no resizes, so the PTY still holds the popup's geometry.
_redock now re-asserts, with force, because the dimensions the dashboard
last sent are the ones it is about to send again.

Reproduced with a dashboard and a popup on one session: before, the pane
sat at 315 columns while the popup rendered 289. After, both report the
same size and the popup's frame matches the pane exactly.

src/web/public/app.js

@@ -1340,6 +1340,14 @@ class CodemanApp {
     this._detachOrphanStrikes.delete(id);
     this.detachedWindows.delete(id);
     this._markDetached(id, false);
+    // Sizing comes back with the session. While the popup owned it the dashboard
+    // sent no resizes, so the PTY still holds the popup's geometry; the session
+    // this window is actually showing has to be re-sized to this window, and
+    // `force` is required because the dimensions the dashboard last sent are
+    // the ones it is about to send again.
+    if (id === this.activeSessionId) {
+      this.sendResize(id, { force: true })?.catch?.(() => {});
+    }
   }
 
   /** Defer a channel-driven redock briefly. A popup *reload* emits 'redocked'