view: every cell of a value over a coordinate index shows — #2060

Found in the review of #2057, which adds the experimental view. It does not block that PR; #2059 fixed the findings that did. Paths refer to #2059's head.

Problem

• The view model lists an axis's entries (indexes[].labels) as the strings of entry_keys(): #0, #1, ….
• It keys a value's entries by indexed_entry_display_name: 0 s, 0.5 s, ….
• web/view/src/values.ts joins the two by string equality. No cell of a value over a coordinate index finds its value, so every cell shows —. Value diffs and selection do not reach those cells either.
• A value over a Fin(n) axis is not drawn as a table: Fin axes are not in indexes at all.

Code: crates/graphcal-project/src/view_model/project.rs (axis labels), crates/graphcal-project/src/view_model/value.rs (entry keys), web/view/src/values.ts.

Reproduction

graphcal view tests/fixtures/valid/range_index.gcl:

{"indexes":[{"name":"TimeStep","labels":["#0","#1","#2"]}], …}

while node x's entries are keyed "0 s", "0.5 s", "1 s".

Proposed fix

• Give each axis entry a { key, display } pair, and let value entries refer to key.
• Include Fin axes in indexes.
• Test the path from Rust through JSON to the page.

This changes the wire format, so it belongs with the other model contract changes.

The review rated this non-critical because no wrong number is shown. It is a candidate for raising, since time series are a main use of the view.