refactor(config): extract config migration logic to testable module

- Extract AGENT_NAME_MAP, HOOK_NAME_MAP, and migration functions to src/shared/migration.ts
- Add comprehensive BDD-style test suite in src/shared/migration.test.ts with 15 test cases
- Export migration functions from src/shared/index.ts
- Improves testability and maintainability of config migration logic

Tests cover:
- Agent name migrations (omo → Sisyphus, OmO-Plan → Planner-Sisyphus)
- Hook name migrations (anthropic-auto-compact → anthropic-context-window-limit-recovery)
- Config key migrations (omo_agent → sisyphus_agent)
- Case-insensitive lookups and edge cases

🤖 GENERATED WITH ASSISTANCE OF [OhMyOpenCode](https://github.com/code-yeongyu/oh-my-opencode)

src/shared/migration.ts

@@ -0,0 +1,94 @@
+import * as fs from "fs"
+import { log } from "./logger"
+
+// Migration map: old keys → new keys (for backward compatibility)
+export const AGENT_NAME_MAP: Record<string, string> = {
+  // Legacy names (backward compatibility)
+  omo: "Sisyphus",
+  "OmO": "Sisyphus",
+  "OmO-Plan": "Planner-Sisyphus",
+  "omo-plan": "Planner-Sisyphus",
+  // Current names
+  sisyphus: "Sisyphus",
+  "planner-sisyphus": "Planner-Sisyphus",
+  build: "build",
+  oracle: "oracle",
+  librarian: "librarian",
+  explore: "explore",
+  "frontend-ui-ux-engineer": "frontend-ui-ux-engineer",
+  "document-writer": "document-writer",
+  "multimodal-looker": "multimodal-looker",
+}
+
+// Migration map: old hook names → new hook names (for backward compatibility)
+export const HOOK_NAME_MAP: Record<string, string> = {
+  // Legacy names (backward compatibility)
+  "anthropic-auto-compact": "anthropic-context-window-limit-recovery",
+}
+
+export function migrateAgentNames(agents: Record<string, unknown>): { migrated: Record<string, unknown>; changed: boolean } {
+  const migrated: Record<string, unknown> = {}
+  let changed = false
+
+  for (const [key, value] of Object.entries(agents)) {
+    const newKey = AGENT_NAME_MAP[key.toLowerCase()] ?? AGENT_NAME_MAP[key] ?? key
+    if (newKey !== key) {
+      changed = true
+    }
+    migrated[newKey] = value
+  }
+
+  return { migrated, changed }
+}
+
+export function migrateHookNames(hooks: string[]): { migrated: string[]; changed: boolean } {
+  const migrated: string[] = []
+  let changed = false
+
+  for (const hook of hooks) {
+    const newHook = HOOK_NAME_MAP[hook] ?? hook
+    if (newHook !== hook) {
+      changed = true
+    }
+    migrated.push(newHook)
+  }
+
+  return { migrated, changed }
+}
+
+export function migrateConfigFile(configPath: string, rawConfig: Record<string, unknown>): boolean {
+  let needsWrite = false
+
+  if (rawConfig.agents && typeof rawConfig.agents === "object") {
+    const { migrated, changed } = migrateAgentNames(rawConfig.agents as Record<string, unknown>)
+    if (changed) {
+      rawConfig.agents = migrated
+      needsWrite = true
+    }
+  }
+
+  if (rawConfig.omo_agent) {
+    rawConfig.sisyphus_agent = rawConfig.omo_agent
+    delete rawConfig.omo_agent
+    needsWrite = true
+  }
+
+  if (rawConfig.disabled_hooks && Array.isArray(rawConfig.disabled_hooks)) {
+    const { migrated, changed } = migrateHookNames(rawConfig.disabled_hooks as string[])
+    if (changed) {
+      rawConfig.disabled_hooks = migrated
+      needsWrite = true
+    }
+  }
+
+  if (needsWrite) {
+    try {
+      fs.writeFileSync(configPath, JSON.stringify(rawConfig, null, 2) + "\n", "utf-8")
+      log(`Migrated config file: ${configPath}`)
+    } catch (err) {
+      log(`Failed to write migrated config to ${configPath}:`, err)
+    }
+  }
+
+  return needsWrite
+}