refactor: remove OMO common config two-layer merge system

Each OMO provider now stores its complete configuration directly in
settings_config.otherFields instead of relying on a shared OmoGlobalConfig
merged at write time. This simplifies the data flow from a 4-tuple
(agents, categories, otherFields, useCommonConfig) to a 3-tuple and
eliminates an entire DB table, two Tauri commands, and ~1700 lines of
merge/sync code across frontend and backend.

Backend:
- Delete database/dao/omo.rs (OmoGlobalConfig struct + get/save methods)
- Remove get/set_config_snippet from settings DAO
- Remove get/set_common_config_snippet Tauri commands
- Replace merge_config() with build_config() in services/omo.rs
- Simplify OmoVariant (remove config_key, known_keys)
- Simplify import_from_local and build_local_file_data
- Rewrite all OMO service tests

Frontend:
- Delete OmoCommonConfigEditor.tsx and OmoGlobalConfigFields.tsx
- Delete src/lib/api/config.ts
- Remove OmoGlobalConfig type and merge preview functions
- Remove useGlobalConfig/useSaveGlobalConfig query hooks
- Simplify useOmoDraftState (remove all common config state)
- Replace OmoCommonConfigEditor with read-only JsonEditor preview
- Clean i18n keys (zh/en/ja)

src/lib/query/omo.ts

@@ -1,14 +1,11 @@
 import { useQuery, useMutation, useQueryClient } from "@tanstack/react-query";
 import { omoApi, omoSlimApi } from "@/lib/api/omo";
-import * as configApi from "@/lib/api/config";
-import type { OmoGlobalConfig } from "@/types/omo";
 
 // ── Factory ────────────────────────────────────────────────────
 
 function createOmoQueryKeys(prefix: string) {
   return {
     all: [prefix] as const,
-    globalConfig: () => [prefix, "global-config"] as const,
     currentProviderId: () => [prefix, "current-provider-id"] as const,
     providerCount: () => [prefix, "provider-count"] as const,
   };
@@ -19,51 +16,13 @@ function createOmoQueryHooks(
   api: typeof omoApi | typeof omoSlimApi,
 ) {
   const keys = createOmoQueryKeys(variant);
-  const snippetKey = variant === "omo" ? "omo" : "omo_slim";
 
   function invalidateAll(queryClient: ReturnType<typeof useQueryClient>) {
-    queryClient.invalidateQueries({ queryKey: keys.globalConfig() });
     queryClient.invalidateQueries({ queryKey: ["providers"] });
     queryClient.invalidateQueries({ queryKey: keys.currentProviderId() });
     queryClient.invalidateQueries({ queryKey: keys.providerCount() });
   }
 
-  function useGlobalConfig(enabled = true) {
-    return useQuery({
-      queryKey: keys.globalConfig(),
-      enabled,
-      queryFn: async (): Promise<OmoGlobalConfig> => {
-        const raw = await configApi.getCommonConfigSnippet(snippetKey);
-        if (!raw) {
-          return {
-            id: "global",
-            disabledAgents: [],
-            disabledMcps: [],
-            disabledHooks: [],
-            disabledSkills: [],
-            updatedAt: new Date().toISOString(),
-          };
-        }
-        try {
-          return JSON.parse(raw) as OmoGlobalConfig;
-        } catch (error) {
-          console.warn(
-            `[${variant}] invalid global config json, fallback to defaults`,
-            error,
-          );
-          return {
-            id: "global",
-            disabledAgents: [],
-            disabledMcps: [],
-            disabledHooks: [],
-            disabledSkills: [],
-            updatedAt: new Date().toISOString(),
-          };
-        }
-      },
-    });
-  }
-
   function useCurrentProviderId(enabled = true) {
     return useQuery({
       queryKey: keys.currentProviderId(),
@@ -86,17 +45,6 @@ function createOmoQueryHooks(
     });
   }
 
-  function useSaveGlobalConfig() {
-    const queryClient = useQueryClient();
-    return useMutation({
-      mutationFn: async (input: OmoGlobalConfig) => {
-        const jsonStr = JSON.stringify(input);
-        await configApi.setCommonConfigSnippet(snippetKey, jsonStr);
-      },
-      onSuccess: () => invalidateAll(queryClient),
-    });
-  }
-
   function useReadLocalFile() {
     return useMutation({
       mutationFn: () => api.readLocalFile(),
@@ -116,10 +64,8 @@ function createOmoQueryHooks(
 
   return {
     keys,
-    useGlobalConfig,
     useCurrentProviderId,
     useProviderCount,
-    useSaveGlobalConfig,
     useReadLocalFile,
     useDisableCurrent,
   };
@@ -135,16 +81,12 @@ const omoSlimHooks = createOmoQueryHooks("omo-slim", omoSlimApi);
 export const omoKeys = omoHooks.keys;
 export const omoSlimKeys = omoSlimHooks.keys;
 
-export const useOmoGlobalConfig = omoHooks.useGlobalConfig;
 export const useCurrentOmoProviderId = omoHooks.useCurrentProviderId;
 export const useOmoProviderCount = omoHooks.useProviderCount;
-export const useSaveOmoGlobalConfig = omoHooks.useSaveGlobalConfig;
 export const useReadOmoLocalFile = omoHooks.useReadLocalFile;
 export const useDisableCurrentOmo = omoHooks.useDisableCurrent;
 
-export const useOmoSlimGlobalConfig = omoSlimHooks.useGlobalConfig;
 export const useCurrentOmoSlimProviderId = omoSlimHooks.useCurrentProviderId;
 export const useOmoSlimProviderCount = omoSlimHooks.useProviderCount;
-export const useSaveOmoSlimGlobalConfig = omoSlimHooks.useSaveGlobalConfig;
 export const useReadOmoSlimLocalFile = omoSlimHooks.useReadLocalFile;
 export const useDisableCurrentOmoSlim = omoSlimHooks.useDisableCurrent;