refactor: consolidate duplicate utility functions (#12439)

* refactor: consolidate duplicate utility functions

- Add escapeRegExp to src/utils.ts and remove 10 local duplicates
- Rename bash-tools clampNumber to clampWithDefault (different signature)
- Centralize formatError calls to use formatErrorMessage from infra/errors.ts
- Re-export formatErrorMessage from cli/cli-utils.ts to preserve API

* refactor: consolidate remaining escapeRegExp duplicates

* refactor: consolidate sleep, stripAnsi, and clamp duplicates

src/agents/pty-keys.ts

@@ -1,3 +1,5 @@
+import { escapeRegExp } from "../utils.js";
+
 const ESC = "\x1b";
 const CR = "\r";
 const TAB = "\t";
@@ -12,10 +14,6 @@ type Modifiers = {
   shift: boolean;
 };
 
-function escapeRegExp(value: string) {
-  return value.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
-}
-
 const namedKeyMap = new Map<string, string>([
   ["enter", CR],
   ["return", CR],