refactor(opencode-skill-loader): split loader and merger into focused modules

Extract skill loading pipeline into single-responsibility modules:
- skill-discovery.ts, skill-directory-loader.ts, skill-deduplication.ts
- loaded-skill-from-path.ts, loaded-skill-template-extractor.ts
- skill-template-resolver.ts, skill-definition-record.ts
- git-master-template-injection.ts, allowed-tools-parser.ts
- skill-mcp-config.ts, skill-resolution-options.ts
- merger/ directory for skill merging logic

src/features/opencode-skill-loader/allowed-tools-parser.ts

@@ -0,0 +1,9 @@
+export function parseAllowedTools(allowedTools: string | string[] | undefined): string[] | undefined {
+  if (!allowedTools) return undefined
+
+  if (Array.isArray(allowedTools)) {
+    return allowedTools.map((tool) => tool.trim()).filter(Boolean)
+  }
+
+  return allowedTools.split(/\s+/).filter(Boolean)
+}