feat: support Codex goal slash command

cli/src/modules/common/slashCommands.test.ts

@@ -116,6 +116,7 @@ describe('listSlashCommands', () => {
         expect(commands.map((command) => command.name)).toEqual(expect.arrayContaining([
             'clear',
             'compact',
+            'goal',
             'plan',
             'status',
             'model',

cli/src/modules/common/slashCommands.ts

@@ -35,6 +35,7 @@ const BUILTIN_COMMANDS: Record<string, SlashCommand[]> = {
     codex: [
         { name: 'clear', description: 'Clear current Codex thread context', source: 'builtin' },
         { name: 'compact', description: 'Compact current Codex thread context', source: 'builtin' },
+        { name: 'goal', description: 'Set, view, pause, resume, or clear a persistent Codex goal', source: 'builtin' },
         { name: 'help', description: 'Show supported HAPI Codex slash commands', source: 'builtin' },
         { name: 'plan', description: 'Enable plan mode; use /plan off to return to default', source: 'builtin' },
         { name: 'default', description: 'Return Codex collaboration mode to default', source: 'builtin' },