fix(saude): never reuse or publish a partial CKAN download

[devgtv]

fix(saude): never reuse or publish a partial CKAN download

download_resource() short-circuits on dest_path.exists() but streams
directly into that path, so a mid-stream drop leaves a truncated file that
the next call happily returns, and the engine then hashes, converts and
uploads it to S3 as the official artifact.

CKAN/Saude also ignore the requested filename and write their own derived
name inside output.parent, so the retry's cleanup of output deleted a path
that never existed. All Saude workers share management/tmp as dest_dir, so
two packages publishing a same-named resource also resolved to the same
dest_path and interleaved their writes.

download_resource() now streams into a sibling ...part file
and os.replace()s it on success, unlinking it on any BaseException, so the
rename is atomic. _download_raw_with_retry() gives each attempt its own
scratch directory and drops the whole directory on retry, which is the only
reliable cleanup when the origin chose the filename itself.

Rebased onto main: the FTP origin keeps its attempt directory, because
_retr_with_resume reads the existing bytes off it to resume with REST --
wiping it between attempts would restart every RETR from byte 0. The
per-attempt directory therefore applies to the origins that need it, and a
test pins both behaviours.

---

This is a re-submission of #353, which was closed without review. The
workflow runs on that PR sat in action_required for three days and then
expired unapproved, so CI never went green.

This workflow run required approval but was not approved before it expired.

Two notes on this one:

• It conflicts semantically with Fix/ftp stale session #367 (Fix/ftp stale session), which
  added REST resume to the FTP path in the same function. Wiping the
  per-attempt directory between retries would restart every RETR from
  byte 0, so the attempt directory is now kept for FTP and the fresh
  directory applies to the origins that need it. A test pins both.
• The suite passes (1787 passed, 6 skipped) and black/isort/flake8 are
  clean. The two remaining failures (test_export.py::TestToSQL::test_basic_duckdb,
  test_dbf_reader.py::test_numpy_object_array_types) also fail on a clean
  main and are unrelated to this change.

[codecov-commenter]

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Codecov Report

❌ Patch coverage is 97.63314% with 4 lines in your changes missing coverage. Please review.
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Files with missing lines	Patch %	Lines
pysus/api/saude/download.py	90.47%	2 Missing ⚠️
pysus/management/sync.py	88.88%	2 Missing ⚠️
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Additional details and impacted files

@@           Coverage Diff           @@
##             main     #370   +/-   ##
=======================================
  Coverage        ?   97.21%           
=======================================
  Files           ?      180           
  Lines           ?    23442           
  Branches        ?        0           
=======================================
  Hits            ?    22789           
  Misses          ?      653           
  Partials        ?        0           

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