Plugin: evaluate Discord subcommand-based native commands

[huntharo]

Problem

Discord may need a subcommand-oriented command surface for this plugin instead of many flat native slash commands.

This matters for two reasons:

• Discord command registration limits and churn are real.
• The plugin command set is already large and likely to grow.

Current Findings

• OpenClaw core already uses a Discord-native subcommand pattern in at least one place: /vc join|leave|status.
• OpenClaw's plugin command definition is currently flat: a plugin command has name, optional nativeNames, and a handler. There is no plugin API for declaring a nested subcommand tree.
• This plugin currently registers many flat commands in index.ts.
• Discord's application command docs currently cap command options at 25, and subcommand/subcommand-group nested options arrays are also capped at 25.
• Discord also documents a global rate limit of 200 application command creates per day per guild.

Implication

If we want /codex <subcommand> or /codex2 <subcommand>, that may require OpenClaw core/plugin API work, not just a local plugin refactor.

Proposed Scope

• Evaluate a Discord-native grouping such as /codex resume|status|fast|model|....
• Decide whether one root command is enough or whether we need multiple roots (/codex, /codex2, etc.).
• Add autocomplete/menu hints for platforms that support subcommands.
• Keep non-Discord channels compatible without forcing them into the same registration shape.

Source Notes

• Plugin command definition is flat and only supports nativeNames: /Users/huntharo/github/openclaw/src/plugins/types.ts:1041
• Existing plugin command list: index.ts:5
• OpenClaw docs for Discord-only /vc join|leave|status: /Users/huntharo/github/openclaw/docs/tools/slash-commands.md:137
• Discord application command docs (official): Application Commands