docs(distribution): Steam is the only channel — the zip, winget and the Store are dead

The site said "Coming soon to Steam" while the app docs still said direct download plus
winget primary with Steam parked. One of them had to move, and the creator's ruling is
Steam exclusive: a free app on Steam with the paid edition as a Steam DLC, and the
$10/month plan sold off-Steam by Polar.

Records the constraint that shapes the code, not just the prose:
- Steamworks requires in-app purchases to use the Steam Wallet (Microtransactions doc,
  quoted in commercial.md), so the monthly is *stated*, never *sold*, inside a Steam
  build; the lifetime is plain DLC bought on the store page and read with BIsDlcInstalled.
- Entitlement is `steamDlcOwned || polarKeyValid`, both resolving to one OutputProfile.
  steam_api64.dll ships beside the exe and is a functional dependency, not the rejected
  "IP protection" native DLL — without it DLC ownership cannot be read. Launched without
  Steam, the app falls back to the free profile rather than refusing to start.
- Signing is moot: Steam installs never meet SmartScreen. Artifact Signing stays on the
  shelf for the day a non-Steam download exists. Year-one fixed cost is ~$115.
- The exe rename must land before the first depot upload — Steamworks warns about
  renaming a live exe.

Distribution.md is rewritten to SteamPipe mechanics (publish output, depot, steamcmd,
DLC wiring, clean-account purchase/refund test). product.md, decisions.md (a new
"Steam exclusive" entry with every dead vector), TASKS.md (Steamworks entitlement row,
Steam packaging row), ai.md, index.md and the TASK 48 banner follow. MyMistakes.md gains
the Steam rules that cost real time today: installs skip SmartScreen, updates are free,
the Wallet rule, and the recurring-billing caveat.

TASKS/task-48-distribution-msix.md

@@ -1,11 +1,10 @@
 # TASK 48 — Distribution & packaging: route decision, MSIX, signing
 
-> ⛔ **THE ROUTE IN THIS FILE IS SUPERSEDED — 2026-10-31.** Distribution is **direct download from
-> `llamacasty.com` (GitHub Releases) + winget primary**; **Steam and the Microsoft Store are parked**,
-> third and fourth. Store IAP is not the billing path — **Polar** is, and the paid delta is output
-> quality. Live policy: [`docs/ai/commercial.md`](../docs/ai/commercial.md); mechanics:
-> [`Distribution.md`](../Distribution.md); cause of death: [`docs/ai/decisions.md`](../docs/ai/decisions.md).
-> The MSIX build steps below are still accurate and remain the parked Store channel's artifact.
+> ⛔ **THE ROUTE IN THIS FILE IS SUPERSEDED — 2026-10-31.** Distribution is **Steam exclusive**: a
+> free app on Steam with the paid edition as a Steam DLC; the monthly plan is sold off-Steam. There
+> is no direct download, no winget and no Store submission. Live policy:
+> [`docs/ai/commercial.md`](../docs/ai/commercial.md); mechanics: [`Distribution.md`](../Distribution.md).
+> The MSIX build steps below still work and are simply unused.
 
 > Catalog: [`TASKS.md`](../TASKS.md) — status and requirements live here.
 > **Research: [`TASKS/research-store-certification.md`](research-store-certification.md)** — the "why".