Raise WebGL retention cap to 32 for multi-worktree hot sets

Reported real-world usage runs 10+ worktrees with ~2 terminals each,
so a cap of 16 evicts inside the active switching set and returns to
those worktrees pay the context rebuild the retention exists to avoid.
32 covers ~10-16 worktrees x 2 panes (~100-250MB worst-case hidden
framebuffers) while staying far under the 128 context budget.

notes/windows-perf-progress.md

@@ -30,10 +30,12 @@ Findings (baseline, this machine):
   ConPTY corruption + perf differences on degraded-mode/fresh-local spawns).
 
 Fixes on this branch (PR #7080 merged in — WebGL release on dispose + stale pty:exit synthesis):
-- A: WebGL context retention across hide/show (pane-webgl-context-retention.ts, LRU cap 16;
-  suspend keeps live contexts; resume repaints instead of recreating). Gated to Windows
-  (getRendererAppPlatform() === 'win32'): macOS/Linux context creation is cheap, so they
-  keep dispose-on-hide and pay no retention GPU-memory cost.
+- A: WebGL context retention across hide/show (pane-webgl-context-retention.ts, LRU cap 32 —
+  sized for ~10-16 worktrees × ~2 terminals hot sets; suspend keeps live contexts; resume
+  repaints instead of recreating). Gated to Windows (getRendererAppPlatform() === 'win32'):
+  macOS/Linux context creation is cheap, so they keep dispose-on-hide and pay no retention
+  GPU-memory cost. Peer note: at least one comparable product raises the context budget to
+  256 and retains unbounded with a session-wide DOM latch on loss; we bound + recover instead.
 - B: useConptyDll for LocalPtyProvider spawns (local-pty-utils.ts) — parity with daemon.
 - D: atlas recovery bursts skip suspended panes (scoped to visible); retained panes repaint
   on resume (shared-atlas invariant preserved).

src/renderer/src/lib/pane-manager/pane-webgl-context-retention.ts

@@ -5,8 +5,9 @@ import type { ManagedPaneInternal } from './pane-manager-types'
 // and recreate it on return — ~5ms on macOS but 100-500ms per pane on Windows
 // (ANGLE → D3D11), paid synchronously on the switch path. With the app-level
 // context budget raised to 128 (#7064), hidden panes can keep their contexts;
-// this LRU cap only bounds hidden-pane GPU memory.
-export const RETAINED_WEBGL_PANE_CAP = 16
+// this LRU cap only bounds hidden-pane GPU memory. Sized for the reported hot
+// set (~10-16 worktrees × ~2 terminals) while staying far under the budget.
+export const RETAINED_WEBGL_PANE_CAP = 32
 
 /** Windows-only: context re-creation is cheap on macOS/Linux GL, so hidden
  *  panes there keep the long-proven dispose-on-hide behavior instead of