feat(ux): implement masonry dashboard layout and immersive focus mode

_bmad/bmm/workflows/4-implementation/dev-story/instructions.xml

@@ -78,7 +78,7 @@
 
     <!-- Non-sprint story discovery -->
     <check if="{{sprint_status}} file does NOT exist">
-      <action>Search {story_dir} for stories directly</action>
+      <action>Search {implementation_artifacts} for stories directly</action>
       <action>Find stories with "ready-for-dev" status in files</action>
       <action>Look for story files matching pattern: *-*-*.md</action>
       <action>Read each candidate story file to check Status section</action>
@@ -114,7 +114,7 @@
     </check>
 
     <action>Store the found story_key (e.g., "1-2-user-authentication") for later status updates</action>
-    <action>Find matching story file in {story_dir} using story_key pattern: {{story_key}}.md</action>
+    <action>Find matching story file in {implementation_artifacts} using story_key pattern: {{story_key}}.md</action>
     <action>Read COMPLETE story file from discovered path</action>
 
     <anchor id="task_check" />

_bmad/bmm/workflows/4-implementation/dev-story/workflow.yaml

@@ -4,12 +4,10 @@ author: "BMad"
 
 # Critical variables from config
 config_source: "{project-root}/_bmad/bmm/config.yaml"
-output_folder: "{config_source}:output_folder"
 user_name: "{config_source}:user_name"
 communication_language: "{config_source}:communication_language"
 user_skill_level: "{config_source}:user_skill_level"
 document_output_language: "{config_source}:document_output_language"
-story_dir: "{config_source}:implementation_artifacts"
 date: system-generated
 
 # Workflow components