fix: respect OPENCODE_CONFIG_DIR environment variable across all config paths

Multiple files were hardcoding ~/.config/opencode paths instead of using
getOpenCodeConfigDir() which respects the OPENCODE_CONFIG_DIR env var.

This broke profile isolation features like OCX ghost mode, where users
set OPENCODE_CONFIG_DIR to a custom path but oh-my-opencode.json and
other configs weren't being read from that location.

Changes:
- plugin-config.ts: Use getOpenCodeConfigDir() directly
- cli/doctor/checks: Use getOpenCodeConfigDir() for auth and config checks
- tools/lsp/config.ts: Use getOpenCodeConfigDir() for LSP config paths
- command loaders: Use getOpenCodeConfigDir() for global command dirs
- hooks: Use getOpenCodeConfigDir() for hook config paths
- config-path.ts: Mark getUserConfigDir() as deprecated
- tests: Ensure OPENCODE_CONFIG_DIR is properly isolated in tests

src/plugin-config.ts

@@ -4,7 +4,7 @@ import { OhMyOpenCodeConfigSchema, type OhMyOpenCodeConfig } from "./config";
 import {
   log,
   deepMerge,
-  getUserConfigDir,
+  getOpenCodeConfigDir,
   addConfigLoadError,
   parseJsonc,
   detectConfigFile,
@@ -94,12 +94,9 @@ export function loadPluginConfig(
   directory: string,
   ctx: unknown
 ): OhMyOpenCodeConfig {
-  // User-level config path (OS-specific) - prefer .jsonc over .json
-  const userBasePath = path.join(
-    getUserConfigDir(),
-    "opencode",
-    "oh-my-opencode"
-  );
+  // User-level config path - prefer .jsonc over .json
+  const configDir = getOpenCodeConfigDir({ binary: "opencode" });
+  const userBasePath = path.join(configDir, "oh-my-opencode");
   const userDetected = detectConfigFile(userBasePath);
   const userConfigPath =
     userDetected.format !== "none"