Resumable HTTP uploads - #97

File types are already assigned at manifest time and preserved by
_file_data_for_partition, so this pass was a no-op for correctly
ingested simulations. Worse, the directory heuristic could promote a
plain FILE entry living next to IMAS data to IMAS, after which the
server rewrites its URI. It also opened every .nc file and scanned
every parent directory on a shared filesystem.

Hand-rolled requests.post/requests.get bypassed the auth gating on
self._server_auth, the gzip compression for large simulations
payloads, and the negotiated self._api_url.

…TF resumable-upload draft

…he http partition

…files after copy

…th overall and per-file progress bars

…p file ingestion

str() around a missing meta value produced a truthy "None" that
suppressed the server's fallback to the authenticated user.

The hand-rolled requests.post bypassed the auth gating on
self._server_auth, the gzip compression for large simulations
payloads, and the negotiated self._api_url. The resumable upload
calls now gate auth the same way.

The two push_http docs commits on this branch edited docs/cli.md and
docs/user_guide.md, both of which were removed by the docs rework that
feature/v1.3-local-push-clean is based on, so they dropped out during the
rebase. Port their net content into the current layout:

- how-to/push-pull.md: how `push` uploads over resumable HTTP against a
  v1.3 remote (with the v1.2 fallback), resumption, chunk sizing via
  Upload-Limit, per-chunk Content-Digest, and the server-side `http`
  partition it stages into.
- reference/server-configuration.md: `server.max_append_size` and the
  `http` partition.
- reference/uri-schemes.md: the internal `http:///` staging URI.

Also switch resumable_upload() to `:param:` docstring fields; the
epydoc-style `@param` block had indented continuation lines that broke
the RST parse and made the -W Sphinx build fail.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>