chore: standardize TypeScript version to 6.0.2 across workspace

- Updated pnpm-workspace.yaml to enforce TypeScript version 6.0.2.
- Replaced legacy TypeScript import with the current version in comparison tools.
- Added ignoreDeprecations setting in tsconfig.base.json to suppress deprecation warnings for baseUrl.
- Introduced TypeScript version policy documentation outlining the rationale and upgrade gate for moving to TypeScript 7.

tools/compare-command-logs.mjs

@@ -1,6 +1,6 @@
 import fs from 'node:fs/promises';
 import path from 'node:path';
-import ts from 'typescript-legacy';
+import ts from 'typescript';
 
 const ROOT_DIR = process.cwd();
 const PHP_ROOT = path.join(ROOT_DIR, 'legacy', 'hwe', 'sammo', 'Command');