feat(lsp): add call hierarchy support for TCL and MOM

Adds LSP call hierarchy support for TCL procedures and MOM events.
A symbol index and identity logic underpin incoming and outgoing calls.
LSP call hierarchy features are wired and changelog/README updated.

- Implement data encoding for call hierarchy items and identity restoration
- Wire LSP server to expose prepare_call_hierarchy, incoming_calls, and outgoing_calls
- Add tests for cross-file calls and edge cases

server/src/lsp_server.py

@@ -51,8 +51,12 @@ from tools.inlay_hint import (
 )
 from tools.navigation import (
     SymbolIdentity,
+    call_hierarchy_identity,
+    call_hierarchy_items,
     definition_identities,
+    incoming_call_hierarchy,
     matching_occurrences,
+    outgoing_call_hierarchy,
     symbol_at_position,
     workspace_symbols,
 )
@@ -629,6 +633,45 @@ def workspace_symbol(params: lsp.WorkspaceSymbolParams):
     return workspace_symbols(LSP_SERVER.navigation_snapshot(), params.query)
 
 
+@LSP_SERVER.feature(lsp.TEXT_DOCUMENT_PREPARE_CALL_HIERARCHY)
+def prepare_call_hierarchy(params: lsp.CallHierarchyPrepareParams):
+    context = _navigation_context(params.text_document.uri, params.position)
+    if context is None:
+        return None
+
+    indexes, _, _, identity = context
+    items = call_hierarchy_items(identity, indexes)
+    return items or None
+
+
+@LSP_SERVER.feature(lsp.CALL_HIERARCHY_INCOMING_CALLS)
+def incoming_calls(params: lsp.CallHierarchyIncomingCallsParams):
+    identity = call_hierarchy_identity(params.item)
+    if identity is None:
+        return []
+
+    indexes = LSP_SERVER.navigation_snapshot()
+    return incoming_call_hierarchy(
+        identity,
+        indexes,
+        definition_identities(indexes),
+    )
+
+
+@LSP_SERVER.feature(lsp.CALL_HIERARCHY_OUTGOING_CALLS)
+def outgoing_calls(params: lsp.CallHierarchyOutgoingCallsParams):
+    identity = call_hierarchy_identity(params.item)
+    if identity is None:
+        return []
+
+    indexes = LSP_SERVER.navigation_snapshot()
+    return outgoing_call_hierarchy(
+        identity,
+        indexes,
+        definition_identities(indexes),
+    )
+
+
 # **********************************************************
 # Linting features end here
 # **********************************************************
@@ -704,6 +747,7 @@ def initialize(params: lsp.InitializeParams) -> lsp.InitializeResult:
             references_provider=True,
             rename_provider=lsp.RenameOptions(prepare_provider=True),
             workspace_symbol_provider=True,
+            call_hierarchy_provider=True,
         )
     )