docs(conf): Suppress sphinx-autodoc-typehints forward reference warnings

why: Forward references in TYPE_CHECKING blocks cannot be resolved at
     doc build time, causing ~69 warnings that obscure other issues
what:
- Add suppress_warnings config to hide forward_reference warnings
- These warnings are cosmetic - types like Self, Server, Session are
  used as string forward references to avoid circular imports

Author: tony

docs/conf.py

@@ -121,6 +121,12 @@
 # sphinx-autodoc-typehints
 always_document_param_types = True
 
+# Suppress warnings for forward references that can't be resolved
+# (types in TYPE_CHECKING blocks used for circular import avoidance)
+suppress_warnings = [
+    "sphinx_autodoc_typehints.forward_reference",
+]
+
 # sphinx-copybutton
 copybutton_prompt_text = (
     r">>> |\.\.\. |> |\$ |\# | In \[\d*\]: | {2,5}\.\.\.: | {5,8}: "