Umlauts/non-ASCII characters corrupted in app log output, independent of container locale/encoding (regression of #990)

[Powerslider26]

What happened?

Title: Umlauts/non-ASCII characters corrupted in app log output, independent of container locale/encoding (regression of #990)

Body:

Related to the old, closed issue #990 ("umlauts getting lost when fetching data from Home Assistant"), which never received a documented fix. I'm seeing the same symptom on a current version and was able to narrow it down further.

Environment:
AppDaemon 4.5.13, Home Assistant OS 18.2 (aarch64/green), installed as the official Home Assistant add-on
Container locale confirmed: LANG=C.UTF-8
python3 -c "import sys; print(sys.stdout.encoding)" inside the container returns utf-8

Symptom:
A German string containing "Ö" (e.g. "AT - Österreich"), read from a Home Assistant input_select entity via self.get_state(), is logged correctly as far as its in-memory representation goes, but appears corrupted in the actual log output.

Diagnosis steps taken:

1. Confirmed via [hex(ord(c)) for c in text] that the Python string itself contains the correct codepoint 0xd6 (U+00D6, "Ö") immediately before logging it.
2. Confirmed via docker logs | grep ... | xxd that the raw bytes captured on the container's stdout are ef bf bd ef bf bd — i.e. the UTF-8 encoding of two separate U+FFFD replacement characters, exactly matching what you'd get from decoding the correct 2-byte UTF-8 sequence (c3 96) one byte at a time with an ASCII-only decoder using errors='replace'.
3. Ruled out: container locale (C.UTF-8), sys.stdout.encoding (utf-8), and the data source (HA websocket state; the same string appears correctly in the corresponding HA entity attribute in Developer Tools → States).

Conclusion: The corruption happens strictly inside AppDaemon's own logging pipeline, between the correctly-encoded Python string and the bytes written to stdout — not in locale handling, not in sys.stdout, and not in the source data.

Steps to reproduce:

python
def initialize(self):
self.log(f"Test: {'Österreich'!r}")

Expected: Test: 'Österreich'
Actual (observed via docker logs): Test: 'sterreich' (with the "Ö" replaced by two U+FFFD-derived bytes)

Happy to provide the full apps.yaml / minimal repro app if useful.

Version

0.18.5

Installation type

Home Assistant add-on

Relevant log output

Relevant code in the app or config file that caused the issue

def initialize(self):
self.log(f"Test: {'Österreich'!r}")

### Anything else?