fix(dcp): correct storage path to match OpenCode's actual location

DCP was failing to find session messages because it was looking in
~/.config/opencode/sessions instead of ~/.local/share/opencode/storage.
Unified all hooks to use getOpenCodeStorageDir() for cross-platform consistency.

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

src/shared/data-path.ts

@@ -2,27 +2,20 @@ import * as path from "node:path"
 import * as os from "node:os"
 
 /**
- * Returns the user-level data directory based on the OS.
- * - Linux/macOS: XDG_DATA_HOME or ~/.local/share
- * - Windows: %LOCALAPPDATA%
+ * Returns the user-level data directory.
+ * Matches OpenCode's behavior via xdg-basedir:
+ * - All platforms: XDG_DATA_HOME or ~/.local/share
  *
- * This follows XDG Base Directory specification on Unix systems
- * and Windows conventions on Windows.
+ * Note: OpenCode uses xdg-basedir which returns ~/.local/share on ALL platforms
+ * including Windows, so we match that behavior exactly.
  */
 export function getDataDir(): string {
-  if (process.platform === "win32") {
-    // Windows: Use %LOCALAPPDATA% (e.g., C:\Users\Username\AppData\Local)
-    return process.env.LOCALAPPDATA ?? path.join(os.homedir(), "AppData", "Local")
-  }
-
-  // Unix: Use XDG_DATA_HOME or fallback to ~/.local/share
   return process.env.XDG_DATA_HOME ?? path.join(os.homedir(), ".local", "share")
 }
 
 /**
  * Returns the OpenCode storage directory path.
- * - Linux/macOS: ~/.local/share/opencode/storage
- * - Windows: %LOCALAPPDATA%\opencode\storage
+ * All platforms: ~/.local/share/opencode/storage
  */
 export function getOpenCodeStorageDir(): string {
   return path.join(getDataDir(), "opencode", "storage")