aw-server-rust & aw-watcher-window: Persistent fatal error "unexpected end of hex escape"

- [x] I am on the [latest](https://github.com/ActivityWatch/activitywatch/releases/latest) ActivityWatch version.
- [x] I have searched the issues of this repo and believe that this is not a duplicate.

- **OS name and version**: Windows 10 LTSC Build 17763
- **ActivityWatch version**: v0.12.1 (rust)

## Describe the bug

The ActivityWatch web UI silently stops updating data, and logs with huge filesizes are created.
The issue persists after you close the explorer.exe window, restart ActivityWatch, and **even through rebooting the computer**.

## To Reproduce

Repro steps are my best guess from looking at the logs, given that I can't re-trigger the bug without somehow fixing it first:
1. Create a new folder named `1719158 (100) - 𝕎𝕚𝕟𝕥𝕖𝕣❄️メイキング`
2. Open this folder with the Windows explorer
3. Watch `AppData\Local\activitywatch\activitywatch\Logs\aw-watcher-window` and `AppData\Local\activitywatch\Logs\aw-server-rust` explode

## Expected behavior

Either keep tracking and reporting data as usual, or fail loudly with an error telling me that the window watcher has stopped working.

## Documentation

Snippet from logs. It's the same messages repeated thousands of times.

aw-server_2022-10-26T14-22-29+0800.log
```
[2022-10-26 14:22:29][INFO][aw_server]: Using DB at path "C:\\Users\\s9menine\\AppData\\Local\\activitywatch\\aw-server-rust\\sqlite.db"
[2022-10-26 14:22:29][INFO][aw_server]: Using aw-webui assets at path "C:\\Users\\s9menine\\AppData\\Local\\Programs\\ActivityWatch\\aw-server-rust\\./static/"
[2022-10-26 14:22:29][INFO][aw_server::endpoints]: Starting aw-server-rust at 127.0.0.1:5600
[2022-10-26 14:22:30][WARN][_]: Data guard `Json < Event >` failed: Parse("{\"id\": null, \"timestamp\": \"2022-10-15T12:34:03.230000+00:00\", \"duration\": 1.059, \"data\": {\"app\": \"explorer.exe\", \"title\": \"D:\\\\[[REDACTED]]\\\\1719158 (100) - \\ud835\\udd4e\\ud835\\udd5a\\ud835\\udd5f\\ud835\"}}", Error("unexpected end of hex escape", line: 1, column: 261)).
[2022-10-26 14:22:30][WARN][_]: No 400 catcher registered. Using Rocket default.
[2022-10-26 14:22:30][WARN][_]: Data guard `Json < Event >` failed: Parse("{\"id\": null, \"timestamp\": \"2022-10-15T12:34:03.230000+00:00\", \"duration\": 1.059, \"data\": {\"app\": \"explorer.exe\", \"title\": \"D:\\\\[[REDACTED]]\\\\1719158 (100) - \\ud835\\udd4e\\ud835\\udd5a\\ud835\\udd5f\\ud835\"}}", Error("unexpected end of hex escape", line: 1, column: 261)).
[2022-10-26 14:22:30][WARN][_]: No 400 catcher registered. Using Rocket default.
[2022-10-26 14:22:30][WARN][_]: Data guard `Json < Event >` failed: Parse("{\"id\": null, \"timestamp\": \"2022-10-15T12:34:03.230000+00:00\", \"duration\": 1.059, \"data\": {\"app\": \"explorer.exe\", \"title\": \"D:\\\\[[REDACTED]]\\\\1719158 (100) - \\ud835\\udd4e\\ud835\\udd5a\\ud835\\udd5f\\ud835\"}}", Error("unexpected end of hex escape", line: 1, column: 261)).
[2022-10-26 14:22:30][WARN][_]: No 400 catcher registered. Using Rocket default.
```

aw-watcher-window_2022-10-26T14-22-29.log
```
2022-10-26 14:22:29 [INFO ]: aw-watcher-window started (aw_watcher_window.main:62)
2022-10-26 14:22:30 [INFO ]: Connection to aw-server established by aw-watcher-window (aw_client.client:429)
2022-10-26 14:22:30 [WARNING]: 400 Client Error: Bad Request for url: http://127.0.0.1:5600/api/0/buckets/aw-watcher-window_[[REDACTED-MACHINE-NAME]]/heartbeat?pulsetime=2.0 (aw_client.client:28)
2022-10-26 14:22:30 [WARNING]: Failed to send request to aw-server, will queue requests until connection is available. (aw_client.client:455)
2022-10-26 14:22:30 [INFO ]: Connection to aw-server established by aw-watcher-window (aw_client.client:429)
2022-10-26 14:22:30 [WARNING]: 400 Client Error: Bad Request for url: http://127.0.0.1:5600/api/0/buckets/aw-watcher-window_[[REDACTED-MACHINE-NAME]]/heartbeat?pulsetime=2.0 (aw_client.client:28)
2022-10-26 14:22:30 [WARNING]: Failed to send request to aw-server, will queue requests until connection is available. (aw_client.client:455)
2022-10-26 14:22:30 [INFO ]: Connection to aw-server established by aw-watcher-window (aw_client.client:429)
2022-10-26 14:22:30 [WARNING]: 400 Client Error: Bad Request for url: http://127.0.0.1:5600/api/0/buckets/aw-watcher-window_[[REDACTED-MACHINE-NAME]]/heartbeat?pulsetime=2.0 (aw_client.client:28)
2022-10-26 14:22:30 [WARNING]: Failed to send request to aw-server, will queue requests until connection is available. (aw_client.client:455)
2022-10-26 14:22:30 [INFO ]: Connection to aw-server established by aw-watcher-window (aw_client.client:429)
```

## Additional context

These were fun to discover.