mystrom: temporary fallback for v1 switches without 'type' (legacy firmware)

[elsi06]

Summary

Older myStrom v1 switches (e.g., firmware 2.x) can omit the type key in their info endpoints. The library then raises a KeyError during get_state, which prevents the integration from setting up in 2025.8.x.

This PR adds a minimal, temporary fallback in the myStrom integration to handle that case until the upstream fix in python‑mystrom is released.

Problem

• HA Core 2025.8.x + v1 devices: setup fails with KeyError: 'type' originating from python‑mystrom when parsing device info
• Affects only legacy v1 firmware; v2+ devices work fine
• Related issue: myStrom Switch CH v1 gets unaviable after update core 2025.8.0 #150264

What this PR changes

• Catches only the specific KeyError during initial switch setup
• Falls back to a small, local “legacy” client for v1 devices that:
  • Reads state via /report (power/Ws/relay/temperature)
  • Toggles via /relay
  • Optionally refreshes firmware/mac if present
• The legacy client is clearly marked TEMPORARY and scoped to the KeyError path only
• No behavior change for v2+ devices or bulbs

Why this is safe

• Extremely narrow scope: activated only if the library throws KeyError for missing type
• Leaves the existing code path untouched for all other devices
• Backwards-compatible; no config or UI changes

Files touched

• homeassistant/components/mystrom/__init__.py — fallback hook on KeyError only
• homeassistant/components/mystrom/legacy.py — NEW; temporary v1 helper
• tests/components/mystrom/test_legacy_v1.py — NEW; covers fallback path

Testing

• New test simulates the KeyError path and verifies:
  • The entity is created and the config entry loads
  • No impact on the normal code path
• Normal flows (v2+) remain unchanged

Follow-up plan

• After a new python‑mystrom release that tolerates missing type is published:
  • Bump the requirement in manifest.json
  • Remove legacy.py and the fallback branch
  • Keep tests green

Related links

• Upstream library fix: Tolerate missing “type” in device info for legacy myStrom v1 switches home-assistant-ecosystem/python-mystrom#60
• Issue: myStrom Switch CH v1 gets unaviable after update core 2025.8.0 #150264

Reviewer checklist

• Scope limited to KeyError path
• No regressions for v2+ devices
• Temporary code clearly labeled and easy to remove post library update
• Test covers the fallback path and passes CI

[home-assistant]

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[home-assistant]

Hey there @fabaff, mind taking a look at this pull request as it has been labeled with an integration (mystrom) you are listed as a code owner for? Thanks!

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Stale

[joostlek]

Okay so 2 things

1. We don't allow integrations to do requests themselves, that should happen in the library. I know you have the PR open, but my teacher used to say "nothing is as definitive as a temporary solution". So I don't want to merge this as is.
2. You mention that it doesn't work in 2025.8.0 anymore because of a keyerror because it is missing type, but on line 54, we use .setdefault to set type to a value, so I am not sure why this would be ommitted now