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.

pnpm-workspace.yaml

@@ -3,6 +3,9 @@ packages:
   - app/*
   - tools/*
 
+overrides:
+  typescript: 6.0.2
+
 allowBuilds:
   '@prisma/engines': true
   esbuild: true