fix(maestro): draft-pane regressions from the integration review

Six findings from reviewing the accumulated blitz/spawn-v2 diff:

- loadRecents restored the seeded cwd but never emitted it, so the leaf's
  draft kept cwd:"" and the next render reseeded the form blank.
- stripDrafts did not recurse, so every half-filled draft in a split tab
  was written to localStorage; the old test passed only because hydrate
  discards draft on the way back in.
- showRawCwd and selectPreset grabbed focus from async init paths, so a
  draft pane stole the caret seconds after mounting.
- .mv-draft inherited no layout once the form left .modal-body.
- onSuccess mounted the new session onto a leaf that may have been closed
  while the POST was in flight, stranding it in no pane.

web/src/styles.css

@@ -2079,6 +2079,12 @@ textarea {
   overflow-y: auto;
   scrollbar-width: thin;
   scrollbar-color: var(--border-strong) transparent;
+  /* The modal form got its stacking and padding from `.modal-body`; in a pane
+     the form is the host, so it carries them itself. */
+  display: flex;
+  flex-direction: column;
+  gap: var(--sp-2);
+  padding: var(--sp-3);
 }
 
 /* pane tools cluster (disconnect / split / close), top-right corner. The attach