Multi-session: allow specifying the SpikeGLX stream once for all sessions

[rly]

Summary

In the multi-session conversion workflow, the SpikeGLX (and any interface with a required non-path parameter such as stream_id) must have its stream entered separately on the Source Data page for every session. Because most users use the same stream across all sessions, this is tedious and error-prone as the session count grows.

Current behavior

• stream_id is a required free-text string in neuroconv's SpikeGLX source schema (e.g. imec0.ap).
• With locate_data enabled, the Locate Data (Path Expansion) page collects per-interface shared settings (base_directory, format_string_path) and auto-locates files across sessions, but it does not collect the stream.
• The Source Data page then renders one form per located session, each requiring stream_id, so the same value is typed once per session.

A "set once" path already exists via the Edit Default Values button on the Source Data page (its global modal keeps stream_id), but it is hard to discover: a small header icon on a later page, with little suggesting that it can set the stream for all sessions.

Proposed change

Surface the shared non-path source-data fields (e.g. stream_id) on the Locate Data page, next to base_directory / format_string_path, backed by the same project.SourceData globals that Edit Default Values already writes. This keeps a single source of truth, lets the stream be set once where users expect it (right after autocomplete locates files), and keeps per-session override behavior.

Scope:

• For each interface on the Locate Data page, pull its required non-path properties from globalState.schema.source_data and add them to that interface's generated schema.
• In beforeSave, route those values into globalState.project.SourceData[interface] (not into the neuroconv/locate payload, which rejects unknown props).
• Keep Edit Default Values as the fallback/override editor, since the Locate Data page only exists when locate_data is enabled.

Relevant files: src/electron/frontend/core/components/pages/guided-mode/data/GuidedPathExpansion.js, src/electron/frontend/core/components/pages/guided-mode/data/GuidedSourceData.js.

[h-mayorquin]

Would not this be fix by only using the converter that does not have the stream id?

[rly]

Yes, SpikeGLXConverterPipe doesn't require stream id and actually cannot take stream id, as is it currently set up. So, GUIDE exposes both SpikeGLXConverterPipe and SpikeGLXRecordingInterface, and only SpikeGLXRecordingInterface allows users to selectively convert a stream.

The core problem also isn't specific to SpikeGLX. TdtRecordingInterface, ExtractSegmentationInterface, and BrukerTiffMultiPlaneConverter - have additional source data fields that would benefit from entering on the Locate Data page (#1086)