### What happened

In the `agents` bar widget, the status card's visibility is gated on
`usageStatusText`, but the text it draws comes from `authHelpText`
(`shell/plugins/agents/Panel.qml:498` and `:512`):

```qml
BorderSurface {
  visible: !!root.provider && String(root.provider.usageStatusText || "") !== ""
  ...
    Text {
      text: root.provider ? String(root.provider.authHelpText || "") : ""
```

A record with a non-empty `usageStatusText` and an empty `authHelpText`
therefore renders the card as an empty red box — border and urgent tint, no
text.

### Why this is reachable

`shell/plugins/agents/README.md` documents adding an agent as an
out-of-tree concern:

> Adding an agent therefore never touches this plugin: ship a collector that
> prints the record contract (see the `claude` and `codex` collectors in
> `bin/`), and the panel gains a tab.

The two fields are independent in that contract, and the combination is a
natural one: an agent whose provider publishes no quota endpoint has a real
status to report ("limits unavailable") but nothing auth could fix, so it has
no help line to offer. I hit this immediately writing a Gemini CLI collector —
Gemini CLI exposes no usage/quota API, so `limits` is empty and there is no
sign-in advice to give.

The shipped collectors don't surface it because all three happen to set both
fields together or neither, so the mismatch is invisible in-tree.

(Related but distinct: #6987 notes there is no Gemini collector. This report
is about the renderer, and would apply to any collector — in-tree or not —
that reports a status without an auth remedy.)

### Latent in stock code too

`bin/omarchy-agent-usage-fireworks:501` builds the pair as:

```python
except FireworksError as error:
  record = base_record(usageStatusText="Fireworks unavailable", authHelpText=str(error))
```

`str(error)` is empty for any zero-argument exception. Every current
`raise FireworksError(...)` passes a message, so this doesn't fire today, but
the empty card is one argument-less raise away.

### Steps to reproduce

1. Write any record to `~/.local/state/omarchy/agents/usage/<id>.json` with
   `usageStatusText` set, `authHelpText` empty, and enough activity for
   `providerHasData()` (e.g. `totalPrompts: 1`):

   ```bash
   jq -n '{schemaVersion:1, id:"demo", name:"Demo", ready:true,
           hasLocalStats:true, totalPrompts:1, totalSessions:1, activeDays:1,
           activeDates:["2026-08-26"], recentDays:[], modelUsage:{},
           limits:[], tierLabel:"",
           usageStatusText:"Demo limits unavailable", authHelpText:""}' \
     > ~/.local/state/omarchy/agents/usage/demo.json
   ```

2. Open the agents panel and switch to the Demo tab.

### Expected

No card when there is no text to put in it. The hero subtitle already carries
`usageStatusText`, so the card adds nothing in this state.

### Actual

An empty red box between the subscription switch and `TOKENS BY DAY`.

### Suggested fix

Gate the card on the text it actually renders:

```qml
visible: !!root.provider && String(root.provider.usageStatusText || "") !== ""
  && String(root.provider.authHelpText || "") !== ""
```

Alternatively have the card fall back to `usageStatusText` when
`authHelpText` is empty — though that duplicates the subtitle.

### System

- Omarchy 4.0.1-1
- Hyprland 0.56.2
- Kernel 7.1.9-arch1-2
- Intel Core i5-1035G7 / Intel Iris Plus Graphics G7

(No diagnostics log attached: `omarchy debug` is not a command in 4.0.1 —
`omarchy commands --all` lists no debug/diagnostics entry.)