fix: correct more workflow file extensions from .yaml to .md

- Update party-mode workflow path: workflow.yaml → workflow.md
- Update brainstorming workflow path: workflow.yaml → workflow.md

src/core/tasks/workflow.xml

@@ -81,7 +81,7 @@
               <action>Continue to next step</action>
             </if>
             <if response="p">
-              <action>Start the party-mode workflow {project-root}/_bmad/core/workflows/party-mode/workflow.yaml</action>
+              <action>Start the party-mode workflow {project-root}/_bmad/core/workflows/party-mode/workflow.md</action>
             </if>
             <if
               response="y">

src/modules/bmb/workflows/agent/data/reference/module-examples/trend-analyst.agent.yaml

@@ -50,5 +50,5 @@ agent:
 
     # Core workflows that exist
     - trigger: "BS or fuzzy match on brainstorm"
-      workflow: "{project-root}/_bmad/core/workflows/brainstorming/workflow.yaml"
+      workflow: "{project-root}/_bmad/core/workflows/brainstorming/workflow.md"
       description: "[BS] Brainstorm trend implications"