fix: defer reactive root disposal in cache cleanups

Same nested-dispose-in-onCleanup bug as 7f36ac2481 but in three more
places: TerminalProvider.disposeAll, PromptProvider.disposeAll, and
scoped-cache.clear() (covers viewCache.clear and comments cache.clear).
All of them synchronously call createRoot dispose() on cached entries
inside onCleanup, which during a server switch nests into the outer
cleanNode cascade and throws TypeError at chunk-*.js:992.

Snapshot the pending disposers, clear the cache synchronously, and
fire the disposers on a microtask so the outer cleanup finishes first.

packages/app/src/context/prompt.tsx

@@ -232,10 +232,13 @@ export const { use: usePrompt, provider: PromptProvider } = createSimpleContext(
     const cache = new Map<string, PromptCacheEntry>()
 
     const disposeAll = () => {
-      for (const entry of cache.values()) {
-        entry.dispose()
-      }
+      // Defer the dispose calls to a microtask; synchronous nested dispose
+      // inside a parent onCleanup corrupts solid-js's in-flight cleanNode
+      // traversal during mass remounts (see context/terminal.tsx for the
+      // same pattern).
+      const pending = Array.from(cache.values(), (entry) => entry.dispose)
       cache.clear()
+      if (pending.length) queueMicrotask(() => pending.forEach((d) => d()))
     }
 
     onCleanup(disposeAll)

packages/app/src/context/terminal.tsx

@@ -364,10 +364,15 @@ export const { use: useTerminal, provider: TerminalProvider } = createSimpleCont
     onCleanup(() => caches.delete(cache))
 
     const disposeAll = () => {
-      for (const entry of cache.values()) {
-        entry.dispose()
-      }
+      // Snapshot disposers, then defer them to a microtask. When this runs
+      // from onCleanup during a parent remount (e.g. switching servers),
+      // calling dispose() synchronously starts a nested cleanNode cascade on
+      // a sibling root while the outer cascade is mid-traversal, corrupting
+      // solid-js's graph walk state and throwing `Cannot read properties of
+      // null (reading '1')` at chunk-*.js:992.
+      const pending = Array.from(cache.values(), (entry) => entry.dispose)
       cache.clear()
+      if (pending.length) queueMicrotask(() => pending.forEach((d) => d()))
     }
 
     onCleanup(disposeAll)