feat: add opencode-skill-loader with 4-source priority system (#331)

* feat: add opencode-skill-loader with 4-source priority system

- Create new opencode-skill-loader feature module independent from Claude Code
- Support 4 source paths with priority: opencode-project > project > opencode > user
  - .opencode/skill/ (opencode-project)
  - .claude/skills/ (project)
  - ~/.config/opencode/skill/ (opencode)
  - ~/.claude/skills/ (user)
- Support both SKILL.md and {SKILLNAME}.md file patterns
- Maintain path awareness for file references (@path syntax)

* feat: integrate opencode-skill-loader into main plugin

- Import and use new skill loader functions
- Load skills from all 4 sources and merge into config.command
- Also merge pluginComponents.skills (previously loaded but never used)

* feat: add skill discovery to slashcommand tool

- Import and use discoverAllSkills from opencode-skill-loader
- Display skills alongside commands in tool description and execution
- Update formatCommandList to handle combined commands and skills

* refactor: remove old claude-code-skill-loader

- Delete src/features/claude-code-skill-loader/ directory (was never integrated into main plugin)
- Update plugin loader import to use new opencode-skill-loader types

* docs: update AGENTS.md for new skill loader

- Update structure to show opencode-skill-loader instead of claude-code-skill-loader
- Update Skills priority order to include all 4 sources

---------

Co-authored-by: sisyphus-dev-ai <sisyphus-dev-ai@users.noreply.github.com>

src/index.ts

@@ -33,6 +33,12 @@ import {
   loadOpencodeProjectCommands,
 } from "./features/claude-code-command-loader";
 import { loadBuiltinCommands } from "./features/builtin-commands";
+import {
+  loadUserSkills,
+  loadProjectSkills,
+  loadOpencodeGlobalSkills,
+  loadOpencodeProjectSkills,
+} from "./features/opencode-skill-loader";
 
 import {
   loadUserAgents,
@@ -523,14 +529,25 @@ const OhMyOpenCodePlugin: Plugin = async (ctx) => {
       const systemCommands = config.command ?? {};
       const projectCommands = (pluginConfig.claude_code?.commands ?? true) ? loadProjectCommands() : {};
       const opencodeProjectCommands = loadOpencodeProjectCommands();
+
+      const userSkills = (pluginConfig.claude_code?.skills ?? true) ? loadUserSkills() : {};
+      const projectSkills = (pluginConfig.claude_code?.skills ?? true) ? loadProjectSkills() : {};
+      const opencodeGlobalSkills = loadOpencodeGlobalSkills();
+      const opencodeProjectSkills = loadOpencodeProjectSkills();
+
       config.command = {
         ...builtinCommands,
         ...userCommands,
+        ...userSkills,
         ...opencodeGlobalCommands,
+        ...opencodeGlobalSkills,
         ...systemCommands,
         ...projectCommands,
+        ...projectSkills,
         ...opencodeProjectCommands,
+        ...opencodeProjectSkills,
         ...pluginComponents.commands,
+        ...pluginComponents.skills,
       };
     },