Fix ruff lint errors in api.py

[rhammen]

Summary

Resolves all 36 ruff check errors in the vendored Zaptec API client (custom_components/zaptec/zaptec/api.py), taking that file from 36 → 0. This chips away at the non-clean ruff check baseline tracked in #258 (CI currently runs ruff check with --exit-zero).

Almost entirely annotations, comment/logging tidy-ups, and two safe latent-type fixes. See the Behavior note below for the one edge case that is not purely cosmetic.

Lint fixes

• Add missing return-type and argument annotations (ANN001/003/201/204/205)
• Replace the mutable default arg for excludes with the None-default pattern (B006)
• Move the "stream already running" precondition raise out of the try (TRY301)
• Bind loop-captured log messages as an immutable default arg (B023)
• Reword a stale FIXME comment to NOTE (TD001/002/003, FIX001)
• Remove commented-out debug lines (ERA001)
• Drop redundant exception args from logging.exception(...) calls (TRY401)
• Remove an unnecessary AsyncGenerator None type arg (UP043)

Two safe latent-type fixes (surfaced while annotating)

• Initialize operation_mode/final_stop_active so they aren't possibly-unbound in is_command_valid's debug log
• Widen Zaptec.__contains__ key param to object for a compatible Mapping override

⚠️ Behavior note (TRY301)

The TRY301 fix moves the "stream already running" precondition raise RuntimeError(...) from inside stream_main's try to before it. Previously that error was caught by the method's own except Exception (logged as "Stream failed", and the finally reset _stream_running); now it propagates to the caller instead. This guard is only hit if stream_main is invoked while a stream is already running — which shouldn't happen in normal use (stream() calls cancel_stream() first, and the manager starts one background task per installation) — and no test exercises it. Arguably more correct (a programming-error guard shouldn't be swallowed by the stream's own handler, and it no longer clobbers a live stream's _stream_running flag), but calling it out since it's the one non-cosmetic change. Happy to use a # noqa: TRY301 instead if maintainers prefer to keep the old swallow-and-log behavior.

Verification

• ruff check custom_components tests — passes (api.py now 0 errors)
• ruff format --diff — clean
• Test suite passes (offline subset; the two live-API fixture files are excluded per the known DNS/env gap)

Follow-up (separate PRs)

This is deliberately scoped to lint-only. I'd like to follow up with staged PRs to raise api.py to high-quality code:

1. Offline unit tests for the core logic (retry/backoff, request status handling, state_to_attrs, is_command_valid, stream_update, hierarchy parsing) — currently the only api test requires live login.
2. Type foundation — annotate instance attrs, parameterize bare generics, Mapping covariance, typed accessors to remove ZaptecBase→Charger/Installation downcasts.
3. Typed API response models (TypedDict/pydantic) to eliminate the pervasive Any on API payloads.
4. Correctness cleanups — the command() variable reuse + int(final_stop_active) guard, explicit kwargs for set_limit_current, instance-scoped debug flags.

Happy to split/reorder these however maintainers prefer.

🤖 Generated with Claude Code

[sveinse]

I think this looks great.