feat(def-navigation): surface last-loaded .def declaration for hover/GoTo

When a block template or address is declared in multiple PSC layers, hover and
Go to Definition now resolve to the effective declaration (the one from the
last-loaded .def file). Find References and Rename still include all
declarations.

- add effective_def_locations(documents, target, uris) helper (returns the last declaration)
- use effective_def_locations in lsp_server for goto/definition endpoints
- change def_hover_markdown to show the effective declaration and append a short
  "_Overrides ..._" note listing overridden declarations
- update changelog and add a test that verifies hover/GoTo reference the last
  loaded declaration while references include all declarations

server/src/lsp_server.py

@@ -55,8 +55,8 @@ from tools.completion_items import (
 from tools.def_navigation import (
     all_def_target_locations,
     def_declarations,
-    def_definition_locations,
     def_hover_markdown,
+    effective_def_locations,
     def_rename_edits,
     def_symbol_at,
 )
@@ -848,12 +848,12 @@ def goto_definition(params: lsp.DefinitionParams):
     context = _navigation_context(params.text_document.uri, params.position)
     if context is None:
         symbol = _tcl_def_symbol(params.text_document.uri, params.position, _word_at(params.text_document.uri, params.position))
-        return symbol and _sorted_locations(def_definition_locations(symbol[0], symbol[1])) or None
+        return symbol and effective_def_locations(symbol[0], symbol[1]) or None
 
     indexes, definitions, _, identity = context
     target = _def_target(identity)
     if target is not None:
-        return _sorted_locations(def_definition_locations(LSP_SERVER.def_documents_snapshot(), target)) or None
+        return effective_def_locations(LSP_SERVER.def_documents_snapshot(), target) or None
     locations = [lsp.Location(uri=index.uri, range=occurrence.range) for index, occurrence in matching_occurrences(identity, indexes, definitions) if occurrence.is_definition]
     return _sorted_locations(locations) or None
 
@@ -1033,7 +1033,7 @@ def def_definition(params) -> list[lsp.Location] | None:
     if context is None:
         return None
     documents, def_uris, target, _ = context
-    return _sorted_locations(def_definition_locations(documents, target, def_uris)) or None
+    return effective_def_locations(documents, target, def_uris) or None
 
 
 @LSP_SERVER.feature(DEF_REQUEST_HOVER)