Sasbdb load

[wpotrzebowski]

Description

This branch adds Load from SASBDB: users can enter a SASBDB dataset ID, fetch metadata and intensity data from the SASBDB REST API, download a local copy, load it through the existing File data pipeline, and enrich the loaded Data1D objects with SASBDB-derived metadata (sample, instrument, publication, Rg, I(0), Dmax, MW, etc.) where the API provides them.

Implementation highlights

• sasbdb_api: HTTP client for https://www.sasbdb.org/rest-api using requests — metadata fetch, URL discovery for intensity files, streamed download to a temp path, robust parsing into SASBDBDatasetInfo (dataclass).
• SASBDBDownloadDialog: Simple UI (dataset ID, Download, progress, status, Help/Cancel); on success returns filepath + parsed info for loading.
• GuiManager.actionLoad_SASBDB: Wired from File → Load from SASBDB (MainWindowUI.ui); calls filesWidget.readData, then _populateSASBDBMetadata to merge API fields into data.sample, data.run, data.instrument, data.title, and meta_data['SASBDB_*'] keys for downstream display.
• GuiUtils: Extends dataset summary text (e.g. Data Explorer / details) with a SASBDB metadata block when SASBDB_code (and related keys) are present.
• Docs: User menu/tools Sphinx sources and in-app help sasbdb_download_help.rst.

Dependencies

• requests (already listed in build_tools/requirements.txt for the project).
• Network access at runtime to reach sasbdb.org for metadata and file download.

How Has This Been Tested?

• Manual (recommended):
  1. File → Load from SASBDB; enter a known valid SASBDB entry ID.
  2. Confirm download completes, data appears in Data Explorer, and plots load as for a normal ASCII/dat file.
  3. Inspect dataset details / summary text for SASBDB fields (code, Rg, publication, etc.) when returned by the API.
  4. Try an invalid ID and confirm a clear error (404 / network).
  5. Offline: confirm failure is handled without crashing (message or log).
• Automated: No dedicated unit tests for sasbdb_api / download dialog were added on this branch; consider mocking HTTP for CI in a follow-up.

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Review Checklist

• Security / network: Timeouts, HTTPS-only usage, and user-visible errors for failed downloads are acceptable.
• Metadata mapping: SASBDB → Sample / Source / meta_data keys do not break loaders or perspectives.
• SASBDBDownloadDialogUI.ui is accompanied by regenerated Python UI (convertUI.py / project build) if required.
• Documentation (menu_bar.rst, tools.rst, sasbdb_download_help.rst) matches the menu label and workflow.
• requests remains available in the installed dependency set for end users (not only dev tooling).

Documentation (check at least one)

• There is nothing that needs documenting
• Documentation changes are in this PR
• There is an issue open for the documentation (link?)

Installers

• There is a chance this will affect the installers, if so
  • Windows installer (GH artifact) has been tested (installed and worked)
  • MacOSX installer (GH artifact) has been tested (installed and worked)
  • Wheels installer (GH artifact) has been tested (installed and worked)

Licensing (untick if necessary)

• The introduced changes comply with SasView license (BSD 3-Clause)