feat(server): index PSC scripts and provide cross-file TclOO navigation/completions

Add PSC (.psc) indexing and share TclOO class metadata across files so class
definitions discovered via PSC layers can be used for completions, signature
help, inlay hints, and "go to definition". Key behavior changes:

- Client file watcher now includes *.psc and .vscode launch paths/tests updated
  to use the postprocessor test folder; .gitignore updated to ignore that folder.
- Server watches .psc changes and refreshes a PSC script index; new
  tools/tcloo_navigation.py exposes tcloo_definition used by the language server
  to resolve cross-file class/constructor/method definitions.
- Language server uses class_snapshot(document.path) when producing TclOO
  completions, signature help, and inlay hints so resolved class metadata is
  available across files.

Also includes related docs/changelog updates, minor code formatting cleanups,
and added tests for PSC/TclOO behavior.

CHANGELOG.md

@@ -1,5 +1,7 @@
 ## Unreleased
 
+- Add Go to Definition for TclOO classes, constructors, and resolved methods, including PSC library definitions
+- Index PSC layer scripts (including external paths and legacy Windows encoding) and share TclOO class metadata across files for completion, signatures, inlay hints, and highlighting
 - Add document-local TclOO method completion for `new`/`create` instances, `my`, and statically inferred return chains
 - Suggest TclOO class names as classes and semantically highlight their declarations and calls
 - Show signature help and parameter inlay hints for resolved TclOO methods and constructors, including optional and variadic arguments