fix(skill-loader): discover skills from parent config dir when using profiles

OPENCODE_CONFIG_DIR pointing to profiles/ subdirectory caused skills at
~/.config/opencode/skills/ to be invisible. Added getOpenCodeSkillDirs()
with the same parent-dir fallback that getOpenCodeCommandDirs() uses.

src/shared/opencode-command-dirs.ts

@@ -22,3 +22,15 @@ export function getOpenCodeCommandDirs(options: OpenCodeConfigDirOptions): strin
     ])
   )
 }
+
+export function getOpenCodeSkillDirs(options: OpenCodeConfigDirOptions): string[] {
+  const configDir = getOpenCodeConfigDir(options)
+  const parentConfigDir = getParentOpencodeConfigDir(configDir)
+
+  return Array.from(
+    new Set([
+      join(configDir, "skills"),
+      ...(parentConfigDir ? [join(parentConfigDir, "skills")] : []),
+    ])
+  )
+}