feat(lsp): add context-aware completion ranking and document highlights

Adds context-aware completion ranking and document highlights for Tcl.
Adds completion_context to distinguish variables and commands.
Wires per-file completion snapshots and ranking into the flow.
Adds document_highlight provider support and tests for highlights.

- Context-aware ranking of completion items using per-file snapshots
- Document highlight provider wired into initialization and tests
- Tests for completion context, ranking, and document highlights

server/tests/python_tests/test_navigation.py

@@ -401,3 +401,62 @@ def test_call_hierarchy_item_uses_whole_proc_range(tmp_path: Path):
     assert items[0].selection_range.start == lsp.Position(line=0, character=5)
     assert items[0].range.start == lsp.Position(line=0, character=0)
     assert items[0].range.end.line == 2
+
+
+def test_document_highlight_marks_local_reads_and_writes(tmp_path: Path, monkeypatch):
+    source = """proc first {} {
+    set value 1
+    puts $value
+    incr value
+}
+proc second {} {
+    set value 2
+    puts $value
+}
+"""
+    document = _document(tmp_path / "highlights.tcl", source)
+    server = TclLanguageServer(name="highlight-test", version="1", max_workers=1)
+    assert server.update_poco_completion_for_file(document)
+    monkeypatch.setattr(lsp_server, "LSP_SERVER", server)
+    position = _position(source, "$value")
+
+    highlights = lsp_server.document_highlight(
+        lsp.DocumentHighlightParams(
+            text_document=lsp.TextDocumentIdentifier(uri=document.uri),
+            position=lsp.Position(position.line, position.character + 1),
+        )
+    )
+
+    assert len(highlights) == 3
+    assert [highlight.kind for highlight in highlights] == [
+        lsp.DocumentHighlightKind.Write,
+        lsp.DocumentHighlightKind.Read,
+        lsp.DocumentHighlightKind.Write,
+    ]
+    assert all(_range_text(source, highlight.range) == "value" for highlight in highlights)
+
+
+def test_document_highlight_marks_proc_definition_and_calls(tmp_path: Path, monkeypatch):
+    source = """proc target {} { return }
+proc caller {} {
+    target
+    target
+}
+"""
+    document = _document(tmp_path / "proc_highlights.tcl", source)
+    server = TclLanguageServer(name="highlight-test", version="1", max_workers=1)
+    assert server.update_poco_completion_for_file(document)
+    monkeypatch.setattr(lsp_server, "LSP_SERVER", server)
+
+    highlights = lsp_server.document_highlight(
+        lsp.DocumentHighlightParams(
+            text_document=lsp.TextDocumentIdentifier(uri=document.uri),
+            position=_position(source, "target"),
+        )
+    )
+
+    assert len(highlights) == 3
+    assert all(
+        highlight.kind == lsp.DocumentHighlightKind.Text
+        for highlight in highlights
+    )