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/merger/config-skill-entry-loader.ts

@@ -0,0 +1,103 @@
+import type { LoadedSkill, SkillMetadata } from "../types"
+import type { SkillDefinition } from "../../../config/schema"
+import type { CommandDefinition } from "../../claude-code-command-loader/types"
+import { existsSync, readFileSync } from "fs"
+import { dirname, isAbsolute, resolve } from "path"
+import { homedir } from "os"
+import { parseFrontmatter } from "../../../shared/frontmatter"
+import { sanitizeModelField } from "../../../shared/model-sanitizer"
+import { parseAllowedTools } from "../allowed-tools-parser"
+
+function resolveFilePath(from: string, configDir?: string): string {
+  let filePath = from
+
+  if (filePath.startsWith("{file:") && filePath.endsWith("}")) {
+    filePath = filePath.slice(6, -1)
+  }
+
+  if (filePath.startsWith("~/")) {
+    return resolve(homedir(), filePath.slice(2))
+  }
+
+  if (isAbsolute(filePath)) {
+    return filePath
+  }
+
+  const baseDir = configDir || process.cwd()
+  return resolve(baseDir, filePath)
+}
+
+function loadSkillFromFile(filePath: string): { template: string; metadata: SkillMetadata } | null {
+  try {
+    if (!existsSync(filePath)) return null
+    const content = readFileSync(filePath, "utf-8")
+    const { data, body } = parseFrontmatter<SkillMetadata>(content)
+    return { template: body, metadata: data }
+  } catch {
+    return null
+  }
+}
+
+export function configEntryToLoadedSkill(
+  name: string,
+  entry: SkillDefinition,
+  configDir?: string
+): LoadedSkill | null {
+  let template = entry.template || ""
+  let fileMetadata: SkillMetadata = {}
+
+  if (entry.from) {
+    const filePath = resolveFilePath(entry.from, configDir)
+    const loaded = loadSkillFromFile(filePath)
+    if (loaded) {
+      template = loaded.template
+      fileMetadata = loaded.metadata
+    } else {
+      return null
+    }
+  }
+
+  if (!template && !entry.from) {
+    return null
+  }
+
+  const description = entry.description || fileMetadata.description || ""
+  const resolvedPath = entry.from
+    ? dirname(resolveFilePath(entry.from, configDir))
+    : configDir || process.cwd()
+
+  const wrappedTemplate = `<skill-instruction>
+Base directory for this skill: ${resolvedPath}/
+File references (@path) in this skill are relative to this directory.
+
+${template.trim()}
+</skill-instruction>
+
+<user-request>
+$ARGUMENTS
+</user-request>`
+
+  const definition: CommandDefinition = {
+    name,
+    description: `(config - Skill) ${description}`,
+    template: wrappedTemplate,
+    model: sanitizeModelField(entry.model || fileMetadata.model, "opencode"),
+    agent: entry.agent || fileMetadata.agent,
+    subtask: entry.subtask ?? fileMetadata.subtask,
+    argumentHint: entry["argument-hint"] || fileMetadata["argument-hint"],
+  }
+
+  const allowedTools = entry["allowed-tools"] || parseAllowedTools(fileMetadata["allowed-tools"])
+
+  return {
+    name,
+    path: entry.from ? resolveFilePath(entry.from, configDir) : undefined,
+    resolvedPath,
+    definition,
+    scope: "config",
+    license: entry.license || fileMetadata.license,
+    compatibility: entry.compatibility || fileMetadata.compatibility,
+    metadata: (entry.metadata as Record<string, string> | undefined) || fileMetadata.metadata,
+    allowedTools,
+  }
+}