Convert all agents to markdown format with frontmatter configuration

- Move all agent prompts from .txt files to .md files
- Add frontmatter configuration to each agent file
- Update opencode.json to reference new markdown files
- Add missing plan.md agent for analysis and planning
- Include docs-writer agent in main configuration
- Remove deprecated prompts/ directory

Benefits:
- Unified markdown format for all agents
- Self-contained agent configuration
- Better maintainability and version control
- Consistent structure across all agents

opencode.json

@@ -2,9 +2,11 @@
   "$schema": "https://opencode.ai/config.json",
   "agent": {
     "build": {
+      "description": "Full-stack development agent with access to all tools for building, testing, and deploying software",
       "mode": "primary",
       "model": "anthropic/claude-sonnet-4-20250514",
-      "prompt": "{file:./prompts/build.txt}",
+      "temperature": 0.5,
+      "prompt": "{file:./.opencode/agent/build.md}",
       "tools": {
         "write": true,
         "edit": true,
@@ -12,9 +14,11 @@
       }
     },
     "plan": {
+      "description": "Analysis and planning agent (read-only, optimized for fast analysis)",
       "mode": "primary",
       "model": "anthropic/claude-haiku-4-20250514",
       "temperature": 0.1,
+      "prompt": "{file:./.opencode/agent/plan.md}",
       "tools": {
         "write": false,
         "edit": false,
@@ -22,11 +26,11 @@
       }
     },
     "cleanup": {
-      "description": "Specialized agent for repository cleanup and maintenance",
+      "description": "Repository cleanup specialist with expertise in maintaining clean, efficient codebases",
       "mode": "subagent",
       "model": "anthropic/claude-sonnet-4-20250514",
       "temperature": 0.2,
-      "prompt": "{file:./prompts/cleanup.txt}",
+      "prompt": "{file:./.opencode/agent/cleanup.md}",
       "tools": {
         "write": true,
         "edit": false,
@@ -45,7 +49,7 @@
       "mode": "subagent",
       "model": "anthropic/claude-sonnet-4-20250514",
       "temperature": 0.1,
-      "prompt": "{file:./prompts/security.txt}",
+      "prompt": "{file:./.opencode/agent/security.md}",
       "tools": {
         "write": false,
         "edit": false,
@@ -58,7 +62,7 @@
       "mode": "subagent",
       "model": "anthropic/claude-sonnet-4-20250514",
       "temperature": 0.1,
-      "prompt": "{file:./prompts/review.txt}",
+      "prompt": "{file:./.opencode/agent/review.md}",
       "tools": {
         "write": false,
         "edit": false,
@@ -71,6 +75,18 @@
           "*": "ask"
         }
       }
+    },
+    "docs-writer": {
+      "description": "Technical writer for creating and maintaining documentation",
+      "mode": "subagent",
+      "model": "anthropic/claude-sonnet-4-20250514",
+      "temperature": 0.3,
+      "prompt": "{file:./.opencode/agent/docs-writer.md}",
+      "tools": {
+        "write": true,
+        "edit": true,
+        "bash": false
+      }
     }
   }
 }