fix(skill): support YAML array format for allowed-tools field (#1163)

Fixes #1021

The allowed-tools field in skill frontmatter now supports both formats:
- Space-separated string: 'allowed-tools: Read Write Edit Bash'
- YAML array: 'allowed-tools: [Read, Write, Edit, Bash]'
- Multi-line YAML array format also works

Previously, skills using YAML array format would silently fail to parse,
causing them to not appear in the <available_skills> list.

Changes:
- Updated parseAllowedTools() in loader.ts, async-loader.ts, and merger.ts
  to handle both string and string[] types
- Updated SkillMetadata type to accept string | string[] for allowed-tools
- Added 4 test cases covering all allowed-tools formats

src/features/opencode-skill-loader/loader.test.ts

@@ -268,6 +268,123 @@ Skill body.
       } finally {
         process.chdir(originalCwd)
       }
+      })
+  })
+
+  describe("allowed-tools parsing", () => {
+    it("parses space-separated allowed-tools string", async () => {
+      // #given
+      const skillContent = `---
+name: space-separated-tools
+description: Skill with space-separated allowed-tools
+allowed-tools: Read Write Edit Bash
+---
+Skill body.
+`
+      createTestSkill("space-separated-tools", skillContent)
+
+      // #when
+      const { discoverSkills } = await import("./loader")
+      const originalCwd = process.cwd()
+      process.chdir(TEST_DIR)
+
+      try {
+        const skills = await discoverSkills({ includeClaudeCodePaths: false })
+        const skill = skills.find(s => s.name === "space-separated-tools")
+
+        // #then
+        expect(skill).toBeDefined()
+        expect(skill?.allowedTools).toEqual(["Read", "Write", "Edit", "Bash"])
+      } finally {
+        process.chdir(originalCwd)
+      }
+    })
+
+    it("parses YAML inline array allowed-tools", async () => {
+      // #given
+      const skillContent = `---
+name: yaml-inline-array
+description: Skill with YAML inline array allowed-tools
+allowed-tools: [Read, Write, Edit, Bash]
+---
+Skill body.
+`
+      createTestSkill("yaml-inline-array", skillContent)
+
+      // #when
+      const { discoverSkills } = await import("./loader")
+      const originalCwd = process.cwd()
+      process.chdir(TEST_DIR)
+
+      try {
+        const skills = await discoverSkills({ includeClaudeCodePaths: false })
+        const skill = skills.find(s => s.name === "yaml-inline-array")
+
+        // #then
+        expect(skill).toBeDefined()
+        expect(skill?.allowedTools).toEqual(["Read", "Write", "Edit", "Bash"])
+      } finally {
+        process.chdir(originalCwd)
+      }
+    })
+
+    it("parses YAML multi-line array allowed-tools", async () => {
+      // #given
+      const skillContent = `---
+name: yaml-multiline-array
+description: Skill with YAML multi-line array allowed-tools
+allowed-tools:
+  - Read
+  - Write
+  - Edit
+  - Bash
+---
+Skill body.
+`
+      createTestSkill("yaml-multiline-array", skillContent)
+
+      // #when
+      const { discoverSkills } = await import("./loader")
+      const originalCwd = process.cwd()
+      process.chdir(TEST_DIR)
+
+      try {
+        const skills = await discoverSkills({ includeClaudeCodePaths: false })
+        const skill = skills.find(s => s.name === "yaml-multiline-array")
+
+        // #then
+        expect(skill).toBeDefined()
+        expect(skill?.allowedTools).toEqual(["Read", "Write", "Edit", "Bash"])
+      } finally {
+        process.chdir(originalCwd)
+      }
+    })
+
+    it("returns undefined for skill without allowed-tools", async () => {
+      // #given
+      const skillContent = `---
+name: no-allowed-tools
+description: Skill without allowed-tools field
+---
+Skill body.
+`
+      createTestSkill("no-allowed-tools", skillContent)
+
+      // #when
+      const { discoverSkills } = await import("./loader")
+      const originalCwd = process.cwd()
+      process.chdir(TEST_DIR)
+
+      try {
+        const skills = await discoverSkills({ includeClaudeCodePaths: false })
+        const skill = skills.find(s => s.name === "no-allowed-tools")
+
+        // #then
+        expect(skill).toBeDefined()
+        expect(skill?.allowedTools).toBeUndefined()
+      } finally {
+        process.chdir(originalCwd)
+      }
     })
   })
 })