Refactor workflow output paths to use a standardized sessions directory structure

- Updated output paths in various command files to reflect the new structure: `.workflow/sessions/{session_id}/` instead of `.workflow/{session_id}/`.
- Adjusted documentation and code comments to ensure consistency across all agents and commands.
- Ensured that all references to session-related files are correctly pointing to the new directory format.

.claude/workflows/cli-templates/prompts/workflow/gemini-solution-design.txt

@@ -5,7 +5,7 @@ Analyze and design optimal solution with comprehensive architecture evaluation a
 □ Analyze current architecture patterns and code structure
 □ Propose solution design with key decisions and rationale
 □ Focus on SOLUTION IMPROVEMENTS and KEY DESIGN DECISIONS
-□ Write output to specified .workflow/{session_id}/.process/ path
+□ Write output to specified .workflow/sessions/{session_id}/.process/ path
 
 ## ANALYSIS PRIORITY
 
@@ -73,7 +73,7 @@ For each target:
 ## OUTPUT REQUIREMENTS
 
 ### Output File
-**Path**: `.workflow/{session_id}/.process/gemini-solution-design.md`
+**Path**: `.workflow/sessions/{session_id}/.process/gemini-solution-design.md`
 **Format**: Follow structure from `~/.claude/workflows/cli-templates/prompts/workflow/analysis-results-structure.txt`
 
 ### Required Sections
@@ -126,6 +126,6 @@ If brainstorming artifacts exist:
 □ Code targets specified in correct format
 □ Feasibility scores provided (X/5)
 □ Final recommendation (PROCEED/RECONSIDER/REJECT)
-□ Output written to .workflow/{session_id}/.process/gemini-solution-design.md
+□ Output written to .workflow/sessions/{session_id}/.process/gemini-solution-design.md
 
 Focus: Comprehensive solution design emphasizing architecture decisions and critical insights.