feat: implement fuzzy search and replace functionality with Levenshtein distance

- Added `applySearchReplace` function to handle search and replace operations with fuzzy matching capabilities.
- Introduced tests for various scenarios including fuzzy matching with typos, exact matches, and handling whitespace differences.
- Created a parser for search/replace blocks to facilitate the new functionality.
- Updated prompts for search-replace operations to clarify usage and examples.
- Added utility functions for text normalization and language detection based on file extensions.
- Implemented a minimal stdio MCP server for local testing with tools for adding numbers and printing environment variables.

e2e-tests/engine.spec.ts

@@ -9,28 +9,11 @@ testSkipIfWindows("send message to engine", async ({ po }) => {
   await po.snapshotMessages({ replaceDumpPath: true });
 });
 
-testSkipIfWindows(
-  "send message to engine - smart context balanced",
-  async ({ po }) => {
-    await po.setUpDyadPro();
-    const proModesDialog = await po.openProModesDialog({
-      location: "home-chat-input-container",
-    });
-    await proModesDialog.setSmartContextMode("balanced");
-    await proModesDialog.close();
-    await po.selectModel({ provider: "Google", model: "Gemini 2.5 Pro" });
-    await po.sendPrompt("[dump] tc=turbo-edits");
-
-    await po.snapshotServerDump("request");
-    await po.snapshotMessages({ replaceDumpPath: true });
-  },
-);
-
-testSkipIfWindows("send message to engine - openai gpt-4.1", async ({ po }) => {
+testSkipIfWindows("send message to engine - openai gpt-5", async ({ po }) => {
   await po.setUpDyadPro();
   // By default, it's using auto which points to Flash 2.5 and doesn't
   // use engine.
-  await po.selectModel({ provider: "OpenAI", model: "GPT 4.1" });
+  await po.selectModel({ provider: "OpenAI", model: "GPT 5" });
   await po.sendPrompt("[dump] tc=turbo-edits");
 
   await po.snapshotServerDump("request");