fix(types): replace all as any with proper type assertions

Eliminate unsafe `as any` casts across 21 non-test source files,
replacing them with specific type annotations:

- Bridge transport: use StdoutMessage type for write/writeBatch calls
- print.ts: type msg.request as Record<string, unknown> for unknown
  SDK control subtypes; use StdoutMessage for output.enqueue()
- API providers (openai/grok/gemini): import ChatCompletion types,
  type streams as AsyncIterable<ChatCompletionChunk>, type request
  bodies as ChatCompletionCreateParamsStreaming
- Computer use executor: use Partial<ResolvePrepareCaptureResult>
  for cross-platform screenshot result
- Components: replace Ink color string casts with proper typing
- Win32 bridge: type stdin as Writable after null check

All 2453 tests pass with 0 failures.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/components/PromptInput/PromptInputFooterSuggestions.tsx

@@ -163,7 +163,7 @@ const SuggestionItemRow = memo(function SuggestionItemRow({
         {paddedDisplayText}
       </Text>
       {tagText ? (
-        <Text color={item.tag === 'local' ? 'yellow' : undefined} dimColor={item.tag !== 'local'}>
+        <Text color={item.tag === 'local' ? ('yellow' as const) : undefined} dimColor={item.tag !== 'local'}>
           {tagText}
         </Text>
       ) : null}