fix(client): retry unmapped TLS transport errors (#3982)

Raw TLS failures can escape HTTPX2's exception normalization and bypass
the SDK's retry and connection-error handling introduced in 3.14.1.
Treat `ssl.SSLError` and `anyio.EndOfStream` as connection errors until
the upstream mappings are fixed, with a short comment linking
pydantic/httpx2#854.

Request failures now honor the retry budget and raise
`APIConnectionError` on exhaustion. Streaming failures are wrapped
without replaying the stream. Generic application exceptions still
propagate unchanged.

Closes #3969.

Validation:
- Client, streaming, and HTTPX2 suites: 368 passed, 22 skipped.
- Regression coverage includes sync/async recovery, exhaustion, disabled
retries, and failures before/after the first streaming event.
- Ruff, targeted mypy, and `git diff --check` passed.
- Tests used frozen dependencies because `uv run --locked` reported an
existing lockfile mismatch; proxy environment variables were unset for
the offline tests.
- Pyright could not run because the repository requires Node 22.22.3 and
the active Node is 18.19.1.