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/hooks/auto-slash-command/executor.ts

@@ -1,12 +1,12 @@
 import { existsSync, readdirSync, readFileSync } from "fs"
 import { join, basename, dirname } from "path"
-import { homedir } from "os"
 import {
   parseFrontmatter,
   resolveCommandsInText,
   resolveFileReferencesInText,
   sanitizeModelField,
   getClaudeConfigDir,
+  getOpenCodeConfigDir,
 } from "../../shared"
 import type { CommandFrontmatter } from "../../features/claude-code-command-loader/types"
 import { isMarkdownFile } from "../../shared/file-utils"
@@ -101,9 +101,10 @@ export interface ExecutorOptions {
 }
 
 async function discoverAllCommands(options?: ExecutorOptions): Promise<CommandInfo[]> {
+  const configDir = getOpenCodeConfigDir({ binary: "opencode" })
   const userCommandsDir = join(getClaudeConfigDir(), "commands")
   const projectCommandsDir = join(process.cwd(), ".claude", "commands")
-  const opencodeGlobalDir = join(homedir(), ".config", "opencode", "command")
+  const opencodeGlobalDir = join(configDir, "command")
   const opencodeProjectDir = join(process.cwd(), ".opencode", "command")
 
   const userCommands = discoverCommandsFromDir(userCommandsDir, "user")