[Packaging] Add a standalone custom-game product distribution profile

[ogyrec-o]

Summary

Add an explicit standalone custom-game product distribution profile for player-facing shipping of a Freven-based game without Vanilla payload, Vanilla builtins, or shared launcher/platform UX unless explicitly chosen.

This is distinct from a standalone template/dev profile.

Problem

Issue #40 freezes that Freven must support standalone custom games as first-class products, not only as “Vanilla plus mods” or as development templates.

We already have follow-up work for:

• generic host runtime profile
• Vanilla product profile
• standalone template/dev profile
• DevKit profile split

But we still need an explicit issue for the shipping product profile of a standalone custom game.

Without this, “standalone game” remains ambiguous between:

• author/developer template setup
• final player-facing shipped product

Those are not the same thing and should not be modeled as the same profile.

Target behavior

A standalone custom-game product profile should support:

• custom executable/product identity
• custom branding
• custom default experience
• custom bundled payload/content
• optional custom builtin registry
• zero-Vanilla by default
• no shared platform/launcher UX unless explicitly chosen
• packaging/distribution suitable for Steam / itch.io / direct download / other standalone channels

Requirements

• The profile must not bundle freven.vanilla unless explicitly opted into.
• The profile must not require Vanilla builtins by default.
• The profile must identify itself as a standalone custom-game product in manifest/profile metadata.
• Product identity / branding / default flow must be shell-owned.
• The packaging layout must be usable as a standalone shipped product rather than only as a development template.
• The profile should be compatible with either:
  • runtime-loaded experiences/mods only
  • custom builtins
  • or a mixed custom product setup
• Docs must explain how this differs from:
  • generic host runtime profile
  • Vanilla product profile
  • standalone template/dev profile
  • DevKit profiles

Non-goals

• Do not build final store upload automation.
• Do not require every custom game to use the generic host/launcher UX.
• Do not remove the generic host or Vanilla product paths.
• Do not redesign unrelated SDK/runtime architecture.
• Do not make Vanilla guest-only.

Deliverables

• Explicit packaging/product profile support for standalone shipped games
• Manifest/profile identity for this product class
• Docs explaining standalone shipped product mode
• Validation/checks ensuring zero-Vanilla by default unless explicitly enabled

Related

• [Architecture] Define the official Freven artifact and distribution profile matrix #40
• [Host Foundation] Define the shell input contract for product identity, bundled content, builtins, and policy #41
• [Boot] Separate generic host foundation APIs from current launcher/devkit shell behavior #42
• [Builtin] Move builtin registration ownership behind shell-provided builtin registries #43
• [Packaging] Add a zero-Vanilla generic host / launcher distribution profile #44
• [Packaging] Add an explicit Vanilla product distribution profile #45
• [Templates] Add a standalone custom-game shell template with zero Vanilla payload #46
• [DevKit] Split DevKit packaging into host-only, Vanilla-enabled, and standalone-game profiles #47
• [Validation/Docs] Add release checks and docs for shell/profile boundaries #48