Surface T-shirt size elements in the backoffice admin

[Elena Peña Tapia (ElePT)]

Summary

The T-shirt size models (ComputeProfile, FunctionSize, Program.default_size) shipped in 0.36.0, but a function's size catalog (its sizes map) and its default size weren't surfaced in the backoffice admin where operators work. This PR adds them, and — as a second step — makes a Fleets function created purely in the admin actually runnable.

Part 1 — Surface the size elements

On the Program (Function) page

• FunctionSizeInline — a function's whole sizes map (each size key → compute profile) is now editable inline on its own page, mirroring the catalog the upload endpoint's sizes payload builds. It renders as "Sizes (compute profile per size)".
• default_size field in its own "Default size" fieldset, rendered directly below the sizes catalog. Its dropdown is restricted to the function's own sizes (Program.clean() rejects a default belonging to another function). The fieldset and the inline are placed adjacent (via a small change_form.html override) and named apart so the two are not mistaken for duplicates.
• sizes_summary changelist column — N (default: s) or -.

On the ComputeProfile page

• sizes_using column — reference count, so an operator sees a profile is in use before editing/deleting it (the FK is PROTECT).

Both changelist columns are annotated to avoid per-row queries.

Part 2 — Make a backoffice-created Fleets function runnable

A Program created purely in the admin previously got only model defaults, skipping a runnable-critical step the upload use case performs:

• CE project assignment. ProgramAdminForm.clean() assigns a Code Engine project to a Fleets function (provider's active project, or the deployment default) via CodeEngineProject.objects.assign_to_program, and blocks the save — with the upload endpoint's own message — when none is available. A Fleets function with no active CE project cannot run, so this fails loud rather than persisting a dead function.

Refactor: promoted _no_ce_project_message → no_ce_project_message so the admin reuses the endpoint's exact wording.

Note: default-size seeding is intentionally left out

An earlier version of this PR also seeded a per-function default size (DEFAULT_FUNCTION_SIZE → DEFAULT_FUNCTION_SIZE_PROFILE) for a size-less Fleets function, mirroring the upload path. That has been removed.

The reason is a design decision that is not in the codebase yet but is coming: the fallback for a function that declared no sizes should be a single shared platform-default FunctionSize row (no function id), resolved at job creation rather than at function creation, so Job.function_size is never null and billing can always read the size off the job. The upload path's existing seeding is untouched (out of scope) and will be revisited when the platform-default work lands.

Scope

• Admin-only. No model or migration changes.
• Does not touch Job.compute_profile (the deprecated string) — that's a separate branch's concern.

Behavioral note (blocking tradeoff)

Because clean() blocks any Fleets save that can't get an active CE project, a legacy/misconfigured Fleets function whose provider has no active project (and no default configured) cannot be saved — even to disable it — until a project is assignable. This is the intended "fail-loud" behavior (mirrors the upload endpoint); the operator assigns a project in the same edit.

Testing

• gateway/tests/test_tshirt_admin.py (16 tests): inline rendering, default_size dropdown scoping, sizes_summary, sizes_using count; CE auto-assign (provider + default paths), blocking when unconfigured / no project / inactive project, operator-chosen project preserved, Ray no-ops; plus two end-to-end admin client tests proving the real add form blocks a non-runnable function and creates a runnable one.
• pylint 10.00/10 on both source files; black clean.

[Elena Peña Tapia (ElePT)]

Verified: admin T-shirt size elements

Ran the backoffice admin locally against a seeded SQLite DB and confirmed each new element renders with real data. Full test suite for the feature passes: pytest tests/test_tshirt_admin.py → 21 passed.

Function list — new "Sizes" column (sizes_summary)
A function with sizes shows the count and the default; a size-less function shows -.
vqe-solver → 3 (default: m), qaoa-runner → -.

Compute profile list — new "Sizes using" column (sizes_using)
Counts how many function sizes point at each profile, so operators see usage before editing or deleting one (the FK is PROTECT). The unused 32x256 profile correctly shows 0.

Function change page — Sizes fieldset, default_size, and the sizes inline
The default_size dropdown is scoped to the function's own sizes. On vqe-solver it lists only vqe-solver (s/m/l), nothing from other functions. The "Sizes (compute profile per size)" inline below maps each size to its compute profile. The Fleets fieldset shows the assigned Code Engine project.