core: move Global module to @opencode-ai/core for centralized path management

Move the Global module from packages/opencode/src/global to packages/core/src/global
to provide a unified location for managing XDG directories and application paths.
This eliminates duplicate path definitions across packages and ensures consistent
access to data, config, cache, state, log, and bin directories throughout the codebase.

packages/core/src/global.ts

@@ -1,7 +1,9 @@
 import path from "path"
+import fs from "fs/promises"
 import { xdgData, xdgCache, xdgConfig, xdgState } from "xdg-basedir"
 import os from "os"
 import { Context, Effect, Layer } from "effect"
+import { Flock } from "./util/flock"
 
 const app = "opencode"
 const data = path.join(xdgData!, app)
@@ -9,7 +11,7 @@ const cache = path.join(xdgCache!, app)
 const config = path.join(xdgConfig!, app)
 const state = path.join(xdgState!, app)
 
-export const Path = {
+const paths = {
   get home() {
     return process.env.OPENCODE_TEST_HOME ?? os.homedir()
   },
@@ -21,31 +23,43 @@ export const Path = {
   state,
 }
 
-export namespace Global {
-  export class Service extends Context.Service<Service, Interface>()("@opencode/Global") {}
+export const Path = paths
 
-  export interface Interface {
-    readonly home: string
-    readonly data: string
-    readonly cache: string
-    readonly config: string
-    readonly state: string
-    readonly bin: string
-    readonly log: string
-  }
+Flock.setGlobal({ state })
 
-  export const layer = Layer.effect(
-    Service,
-    Effect.gen(function* () {
-      return Service.of({
-        home: Path.home,
-        data: Path.data,
-        cache: Path.cache,
-        config: Path.config,
-        state: Path.state,
-        bin: Path.bin,
-        log: Path.log,
-      })
-    }),
-  )
+await Promise.all([
+  fs.mkdir(Path.data, { recursive: true }),
+  fs.mkdir(Path.config, { recursive: true }),
+  fs.mkdir(Path.state, { recursive: true }),
+  fs.mkdir(Path.log, { recursive: true }),
+  fs.mkdir(Path.bin, { recursive: true }),
+])
+
+export class Service extends Context.Service<Service, Interface>()("@opencode/Global") {}
+
+export interface Interface {
+  readonly home: string
+  readonly data: string
+  readonly cache: string
+  readonly config: string
+  readonly state: string
+  readonly bin: string
+  readonly log: string
 }
+
+export const layer = Layer.effect(
+  Service,
+  Effect.gen(function* () {
+    return Service.of({
+      home: Path.home,
+      data: Path.data,
+      cache: Path.cache,
+      config: Path.config,
+      state: Path.state,
+      bin: Path.bin,
+      log: Path.log,
+    })
+  }),
+)
+
+export * as Global from "./global"