fix: replace HTTP status string parsing with structured HTTPError

[Faerkeren]

Closes #79

Validity Assessment

Valid bug. get_state() detected missing entities by parsing "HTTP 404" out of an exception message string. This is fragile: a message format change or a coincidental match in a response body could silently alter behavior. Status codes are structured data and should be treated as such.

Fix

New exception: HTTPError

Added HTTPError(status, method, path, body) to exceptions.py, derived from HAClientError. Carries the HTTP status code, method, path, and body as typed attributes. The str() representation is backward-compatible ("HTTP 404 from GET /api/states/foo: ...").

class HTTPError(HAClientError):
    def __init__(self, status: int, method: str, path: str, body: str) -> None: ...
    status: int
    method: str
    path: str
    body: str

HTTPError is exported from the top-level haclient package.

_request() — rest_aiohttp.py

Raises HTTPError instead of generic HAClientError for all non-401 HTTP failures.

get_state() — rest_aiohttp.py

Before:

except HAClientError as err:
    if "HTTP 404" in str(err):  # brittle string match
        return None

After:

except HTTPError as err:
    if err.status == 404:        # structured check
        return None

Tests / Checks Run

• test_request_server_error — updated to assert the raised exception is HTTPError with correct status, method, path attributes, and that it is still an instance of HAClientError.
• test_http_error_attributes — new: verifies all structured attributes and the string representation.
• test_get_state_returns_none_only_for_404 — new: verifies get_state() returns None only for a real 404, not for other scenarios.
• test_get_state_reraises_non_404_http_error — new: verifies get_state() re-raises HTTPError when status is not 404 (e.g. 500).

Suite results:

• pytest: 307 passed, coverage 97.16% (threshold 95%)
• ruff check + ruff format --check: all checks passed
• mypy src: no issues found