fix(ui): expose isStaticSpa toggle for nixpacks + publish directory

[elisiumm]

What

Exposes the Is Static SPA toggle in the Build Type form for Nixpacks + Publish Directory, and stops the flag from being dropped on save in that mode.

Fixes #4993

Why

The backend already supports isStaticSpa for Nixpacks builds: when a publishDirectory is set, nixpacks.ts calls getStaticCommand(application), which reads isStaticSpa and, when true, generates the nginx config with the SPA fallback try_files $uri $uri/ /index.html.

However, the UI form in apps/dokploy/components/dashboard/application/build/show.tsx only wired isStaticSpa into the static variant of the z.discriminatedUnion. As a result, for buildType: nixpacks:

• the toggle was never rendered, so there was no way to enable the SPA fallback from the UI;
• the field was omitted from the submit payload, so any Build config save in Nixpacks mode reset the value to null.

Net user-facing effect: a deep-link hard-refresh / cold-start on a client-side route (/planning, /users/:id, …) returned a 404 from nginx because try_files was absent — the SPA never loaded on first hit. This is a very common setup for monorepos where the Static build type can't run the build step.

The Dosu triage on #4993 confirmed the gap and traced it to an integration oversight between #297 (Nixpacks publishDirectory support) and #1931 (which added the isStaticSpa toggle only for static). Railpack does not call getStaticCommand, so it is intentionally left untouched.

Changes

Single file, UI-only, no backend change:

• Add isStaticSpa: z.boolean().default(false) to the nixpacks discriminated-union variant.
• Mirror it in resetData's nixpacks case.
• Include isStaticSpa in the submit payload for static or nixpacks (else null).
• Render the existing SPA checkbox when buildType === nixpacks && publishDirectory is set — reusing the exact pattern of the static block, with a distinct DOM id (checkboxIsStaticSpaNixpacks) to avoid a duplicate id.

Testing

• pnpm --filter=dokploy run typecheck (tsc --noEmit): clean, no diagnostics. The discriminated union now types isStaticSpa: boolean for nixpacks, and resetData stays exhaustive/symmetric with static.
• pnpm exec biome check on the touched file: clean, no fixes applied.

Honest disclosure per CONTRIBUTING: I verified the change by typecheck + Biome + code review of the schema/reset/render paths, but I did not run the full local stack (Docker + Postgres + server:3000) for an interactive browser round-trip. The backend path this restores (getStaticCommand → nginx SPA fallback) is already proven working on a real running instance — with isStaticSpa forced directly in the DB, the generated nginx serves index.html with HTTP 200 on client routes; this PR only reconnects the UI plumbing to that already-working backend path. Happy to add a screencast or a scoped test on show.tsx if maintainers prefer.

Greptile Summary

This PR exposes the existing SPA setting for Nixpacks applications that specify a publish directory and preserves that setting through build-configuration saves.

• Adds isStaticSpa to the Nixpacks form schema and reset data.
• Includes the Nixpacks SPA value in the submitted build configuration.
• Conditionally renders the SPA checkbox when Nixpacks static publishing is active.

Confidence Score: 5/5

The PR appears safe to merge, with no concrete changed-code failure identified.

The added field is consistently represented in validation, reset state, submission, and rendering, while the checkbox visibility matches the Nixpacks builder condition that activates static publishing.

_{Reviews (1): Last reviewed commit: "fix(ui): expose isStaticSpa toggle for n..." | Re-trigger Greptile}