feat(dispatch): wire marketplace plugin commands into slash command dispatch

Connect the existing plugin loader infrastructure to both slash command
dispatch paths (executor and slashcommand tool), enabling namespaced
commands like /daplug:run-prompt to resolve and execute.

- Add plugin discovery to executor.ts discoverAllCommands()
- Add plugin discovery to command-discovery.ts discoverCommandsSync()
- Add "plugin" to CommandScope type
- Remove blanket colon-rejection error (replaced with standard not-found)
- Update slash command regex to accept namespaced commands
- Thread claude_code.plugins config toggle through dispatch chain
- Add unit tests for plugin command discovery and dispatch

Closes #2019

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Codex <noreply@openai.com>

src/plugin/hooks/create-skill-hooks.ts

@@ -1,5 +1,5 @@
 import type { AvailableSkill } from "../../agents/dynamic-agent-prompt-builder"
-import type { HookName } from "../../config"
+import type { HookName, OhMyOpenCodeConfig } from "../../config"
 import type { LoadedSkill } from "../../features/opencode-skill-loader/types"
 import type { PluginContext } from "../types"
 
@@ -13,12 +13,20 @@ export type SkillHooks = {
 
 export function createSkillHooks(args: {
   ctx: PluginContext
+  pluginConfig: OhMyOpenCodeConfig
   isHookEnabled: (hookName: HookName) => boolean
   safeHookEnabled: boolean
   mergedSkills: LoadedSkill[]
   availableSkills: AvailableSkill[]
 }): SkillHooks {
-  const { ctx, isHookEnabled, safeHookEnabled, mergedSkills, availableSkills } = args
+  const {
+    ctx,
+    pluginConfig,
+    isHookEnabled,
+    safeHookEnabled,
+    mergedSkills,
+    availableSkills,
+  } = args
 
   const safeHook = <T>(hookName: HookName, factory: () => T): T | null =>
     safeCreateHook(hookName, factory, { enabled: safeHookEnabled })
@@ -30,7 +38,11 @@ export function createSkillHooks(args: {
 
   const autoSlashCommand = isHookEnabled("auto-slash-command")
     ? safeHook("auto-slash-command", () =>
-        createAutoSlashCommandHook({ skills: mergedSkills }))
+        createAutoSlashCommandHook({
+          skills: mergedSkills,
+          pluginsEnabled: pluginConfig.claude_code?.plugins ?? true,
+          enabledPluginsOverride: pluginConfig.claude_code?.plugins_override,
+        }))
     : null
 
   return { categorySkillReminder, autoSlashCommand }