feat: wire context-window-recovery callers to async SDK/HTTP variants on SQLite

- empty-content-recovery: isSqliteBackend() branch delegating to extracted
  empty-content-recovery-sdk.ts with SDK message scanning
- message-builder: sanitizeEmptyMessagesBeforeSummarize now async with SDK path
  using replaceEmptyTextPartsAsync/injectTextPartAsync
- target-token-truncation: truncateUntilTargetTokens now async with SDK path
  using findToolResultsBySizeFromSDK/truncateToolResultAsync
- aggressive-truncation-strategy: passes client to truncateUntilTargetTokens
- summarize-retry-strategy: await sanitizeEmptyMessagesBeforeSummarize
- client.ts: derive Client from PluginInput['client'] instead of manual defs
- executor.test.ts: .mockReturnValue() → .mockResolvedValue() for async fns
- storage.test.ts: add await for async truncateUntilTargetTokens

src/hooks/anthropic-context-window-limit-recovery/summarize-retry-strategy.ts

@@ -61,7 +61,7 @@ export async function runSummarizeRetryStrategy(params: {
 
     if (providerID && modelID) {
       try {
-        sanitizeEmptyMessagesBeforeSummarize(params.sessionID)
+        await sanitizeEmptyMessagesBeforeSummarize(params.sessionID, params.client)
 
         await params.client.tui
           .showToast({