[Bug]: Update failed: no release asset matched the current platform (linux/x86_64)

### Pre-flight checklist

- [x] I searched [existing issues](https://github.com/AprilNEA/OpenLogi/issues?q=is%3Aissue) and this is not a duplicate.
- [x] I am on the [latest release](https://github.com/AprilNEA/OpenLogi/releases/latest) or a recent `master` build.
- [x] I quit **Logi Options+** before running OpenLogi (the two apps fight over HID++ access and only one can own a receiver at a time).

### Which part of OpenLogi?

GUI (desktop app)

### OpenLogi version

0.6.24

### Operating system

Linux

### OS version & architecture

Ubuntu 26.04 Win 64

### Device model

MX Master S3

### How is the device connected?

Bluetooth (direct, no receiver)

### Affected area(s)

- [ ] Device discovery / detection
- [ ] Button remapping
- [ ] DPI control
- [ ] SmartShift
- [ ] Per-application profiles
- [ ] Battery status
- [ ] Settings / configuration (TOML)
- [x] Auto-update
- [ ] Menu bar / tray
- [ ] Other

### What happened?

I'm on Ubuntu 26.04 and I can't use the update feature in the app because it gives me the following error message:

### Steps to reproduce

1. Go to Settings > Updates
2. Click the Check for Updates button
3. Observe the following error message `Update failed: no release asset matched the current platform (linux/x86_64)`

### Diagnostics report

```markdown
### OpenLogi Diagnostics

**App**
- OpenLogi (GUI): v0.6.27 (release)
- Agent: v0.6.27 (connected)
- IPC protocol: GUI 16 / agent 16
- Inventory: ready
- OS: Linux (x86_64)
- Locale: en-US (UI: follow system)
- Accessibility: granted · Input hook: installed
- Launch at login: no · Menu bar: yes · Update check: on
- Running from: source build (dev)
- Config: schema 4 · 1 configured device(s) · thumbwheel 14

**Assets**
- Source: user cache · Index: loaded (210 models) · User cache: present
- Cache path: ~/.local/share/openlogi/assets · Bundle assets: absent

**Devices (1)**
- MX Master 3S — mouse (codename: MX Master 3S)
- Connection: Bluetooth (direct) · Online: yes · Battery: 90% (discharging, full)
- Capabilities: buttons=yes, pointer=yes, lighting=no
- Model: 0b034 (model-ids: b034/0000/0000, ext-model: 00)
- Transports: BTLE
- Render: mx_master_3s · direct
```

### `openlogi list` output

```text
Logitech MX Master 3S (—, vid=046d pid=b034)
└─ slot 255 ● MX Master 3S (mouse, wpid=?, battery=90% full (discharging))
model_ids=[b034,0000,0000] ext=00 serial=2540APFBE888 unit_id=8d0755ec transports=btle
```

### Logs

```shell

```

### macOS permissions (if applicable)

- [ ] OpenLogi has **Accessibility** permission (needed to remap buttons via the event tap).
- [ ] OpenLogi has **Input Monitoring** permission (needed for Bluetooth-direct devices and capture).

Start at Settings > Updates and trace the update check using the reported linux/x86_64 platform and release assets. Compare the asset matching logic with the assets published for the current release, then verify that Check for Updates succeeds on Ubuntu Linux x86_64 instead of reporting that no asset matched.

Written by the indexing model from the issue text.