Use Sphinx .. deprecated:: directive for deprecated aggregator params

Aligns deprecation docstrings on LLMUserAggregatorParams and
LLMAssistantAggregatorParams with CONTRIBUTING.md conventions:
present-tense parameter descriptions plus a `.. deprecated:: 1.2.0`
directive noting replacement and 2.0.0 removal. Also adds a runtime
DeprecationWarning for `user_turn_completion_config`, which previously
had no warning despite being deprecated.

src/pipecat/processors/aggregators/llm_response_universal.py

@@ -132,12 +132,21 @@ class LLMUserAggregatorParams:
             marker at the start of each response: ✓ (complete), ○
             (incomplete short), or ◐ (incomplete long). Incomplete
             responses are suppressed and timeouts trigger re-prompting.
+
+            .. deprecated:: 1.2.0
+                Use ``user_turn_strategies=FilterIncompleteUserTurnStrategies()``
+                instead. Will be removed in version 2.0.0.
+
         user_turn_completion_config: [DEPRECATED] Configuration for turn
             completion behavior including custom instructions, timeouts, and
             prompts. Only used when filter_incomplete_user_turns is True
             (deprecated path) — for the new strategy-based API, pass the config
             directly to ``FilterIncompleteUserTurnStrategies(config=...)``.
 
+            .. deprecated:: 1.2.0
+                Pass the config directly to
+                ``FilterIncompleteUserTurnStrategies(config=...)`` instead.
+                Will be removed in version 2.0.0.
     """
 
     add_tool_change_messages: bool = False
@@ -166,6 +175,15 @@ class LLMUserAggregatorParams:
                 stacklevel=2,
             )
 
+        if self.user_turn_completion_config is not None:
+            warnings.warn(
+                "LLMUserAggregatorParams.user_turn_completion_config is deprecated. "
+                "Pass the config directly to "
+                "FilterIncompleteUserTurnStrategies(config=...) instead.",
+                DeprecationWarning,
+                stacklevel=2,
+            )
+
 
 @dataclass
 class LLMAssistantAggregatorParams:
@@ -201,6 +219,11 @@ class LLMAssistantAggregatorParams:
     # ---------------------------------------------------------------------------
     # Deprecated field names — kept for backward compatibility.
     # Use enable_auto_context_summarization and auto_context_summarization_config instead.
+    #
+    # .. deprecated:: 1.2.0
+    #     Use ``enable_auto_context_summarization`` and
+    #     ``auto_context_summarization_config`` instead. Will be removed in
+    #     version 2.0.0.
     # ---------------------------------------------------------------------------
     enable_context_summarization: bool | None = None
     context_summarization_config: LLMContextSummarizationConfig | None = None