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/infra/env-file.ts

@@ -1,10 +1,6 @@
 import fs from "node:fs";
 import path from "node:path";
-import { resolveConfigDir } from "../utils.js";
-
-function escapeRegExp(value: string): string {
-  return value.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
-}
+import { escapeRegExp, resolveConfigDir } from "../utils.js";
 
 export function upsertSharedEnvVar(params: {
   key: string;