docs: Fix documentation mismatches with actual client behavior (#958)

Fixes 12 documentation issues found by an engineering audit, where docs,
examples, or docstrings contradict what the client actually does:

- The custom HTTP client guide example (`HttpxClient`) now raises
`ApifyApiError` for error responses instead of returning them raw, and
the guide documents this part of the `call` contract (resource clients
rely on it, e.g. to translate a 404 into a `None` return value).
- The streaming concepts page no longer claims all three streaming
methods yield a raw `impit.Response` — it now describes the actual
yielded value per method (`stream_record` yields a `dict` with the
response under `value`, `stream` and `stream_record` may yield `None`).
- The pagination concepts page no longer lists `ListOfRequests` among
page models exposing `total`/`offset`/`count`; it now explains its
cursor-based pagination via `next_cursor`.
- The logging formatter example no longer references `%(status_code)s`
(absent on most records, causing logging errors) and no longer attaches
a duplicate handler; the page notes which properties are present on
every record.
- The upgrading-to-v3 guide cross-links now include the site baseUrl
(`/api/client/python/...`), fixing 6 links that 404ed on the published
site.
- The conda instruction for the brotli extra installs `brotli-python`
(the Python bindings) instead of `brotli` (the C library).
- `RunClient.resurrect` docstrings cite the real `SUCCEEDED` status
instead of the nonexistent `FINISHED`.
- `wait_for_finish` docstrings in `RunClient` and `BuildClient` spell
the terminal status as `TIMED-OUT` (the real literal) instead of
`TIMED_OUT`.
- The quick-start page refers to the `Run` model's `default_dataset_id`
attribute instead of the v2-era run dictionary with `defaultDatasetId`.
- The README dataset example passes `fields` as `list[str]` per the
signature instead of a comma-separated string.
- The README quick-start examples handle the `Run | None` return of
`call()` instead of accessing attributes on a possible `None`.
- The timeouts concepts page states that `no_timeout` is capped at 24
hours by the default client instead of claiming it disables the timeout
entirely.

*✍️ Drafted by Claude Code*