bug: confirm_action slash-command flow re-adds history and double-fires telemetry vs the shell-confirmation path

## What happened?

The `confirm_action` slash-command flow re-invokes `handleSlashCommand()` with the original raw invocation but without the `addToHistory: false` flag its sibling (`confirm_shell_commands`) passes. The recursive call therefore re-executes the history-add at the top of command processing and re-fires `logSlashCommand()` in the finally block: **two** SUCCESS `SlashCommandEvent`s per confirmed action, and the user's command text is added to history twice unless the consecutive-duplicate suppression in `useHistoryManager.addItem` happens to mask it (which breaks whenever any other item lands between dialog open and confirm).

## Affected code

`packages/cli/src/ui/hooks/slashCommandProcessor.ts:644-650` (sibling path, correct):

```ts
return await handleSlashCommand(
result.originalInvocation.raw,
new Set(approvedCommands),
undefined,
false, // Do not add to history again
);
```

`packages/cli/src/ui/hooks/slashCommandProcessor.ts:676-680` (`confirm_action`, missing flag):

```ts
return await handleSlashCommand(
result.originalInvocation.raw,
undefined,
true,
);
```

## How can this be reproduced?

1. Run any command that routes through `confirm_action` (e.g., `/memory add ...` style confirmation).
2. Confirm the dialog.
3. Check telemetry: two SlashCommandEvent records for one interaction.
4. For visible duplication: trigger an async info/error item while the dialog is open, then confirm — the command bubble appears twice in history.

## What did you expect to happen?

Behavior parity with the shell-confirmation path: no duplicate history entry, single telemetry event.

## Suggested direction

Mirror the sibling call: pass the same approved-commands set semantics where applicable and `false` for `addToHistory`.

---

*Found by source audit on current `main` (commit `5411f113c`); platform-independent. No open issue/PR covering this was found (searched: slash command telemetry duplicated).*

Open packages/cli/src/ui/hooks/slashCommandProcessor.ts around lines 644-650 and 676-680, and compare the confirm_shell_commands and confirm_action recursive calls. Reproduce a confirm_action flow, including an async info/error item while the dialog is open, then verify that one confirmation produces one telemetry event and one history entry.

Written by the indexing model from the issue text.