fix(agent): critical UnboundLocalError on Agent() without max_budget

PR #1635 introduced a local 'from ... import ExecutionConfig' inside
__init__ (line 743 inside 'if max_budget is not None:' branch).
Per Python scoping rules, a name assigned anywhere in a function is
treated as local throughout the entire function. When max_budget is
None (the common case), the local branch never executes but line 777
still hits 'ExecutionConfig' and raises UnboundLocalError, breaking
every Agent() instantiation without max_budget.

ExecutionConfig is already imported at module level (line 162-166).
Only resolve_execution needs the local lazy import.

Test: tests/unit/agent/test_scientific_writer_agent.py surfaced this;
now passes along with 311 other agent unit tests.

Author: praisonai-bot

src/praisonai-agents/praisonaiagents/agent/agent.py

@@ -740,7 +740,12 @@ def __init__(
 
         # Handle max_budget convenience parameter
         if max_budget is not None:
-            from ..config.feature_configs import ExecutionConfig, resolve_execution
+            # NOTE: ExecutionConfig is imported at module level (see top of file).
+            # Do NOT re-import it locally here — a local import statement would
+            # make Python treat ExecutionConfig as a local name throughout this
+            # entire __init__ function and break the branch below that uses it
+            # when max_budget is None (UnboundLocalError).
+            from ..config.feature_configs import resolve_execution
             if execution is None:
                 execution = ExecutionConfig(max_budget=max_budget)
             else: