chore: remove the abandoned prototypes and archive what described them

portal/, kanban/ and agente/ were 2,034 lines implementing the original
Tiny-first model: token upload links, a second SQLite Kanban, a factory agent.
Nothing imported or started any of it, and several endpoints took the acting
user from the request body with no authentication at all. Their real cost was
that a reader arriving at this repository found two Kanbans and two portals and
had to work out which one was real. The root schema.sql and .env.exemplo went
with them: both code paths load local/schema.sql, and having .env.exemplo beside
.env.example differing by one letter was a trap rather than a convenience.

The documents describing that model are archived rather than deleted. They
record decisions and reasoning the current documents do not repeat, so they are
worth keeping as background, with a header saying plainly that they are not
instructions.

README.md keeps its business case — the capacity figures and the cost argument
are still the reason this project exists — but now states where the prototype
documentation begins and that the code it describes is gone.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

README.md

@@ -14,6 +14,16 @@
 > a arquitetura, o código e o que ainda depende de resposta.
 > Base: conversas de 29 e 30/08/2026 com Marcus.
 
+
+> **2026-09-21.** Everything below this line is the original prototype
+> documentation. The code it describes (`portal/`, `kanban/`, `agente/`, the root
+> `schema.sql`, `.env.exemplo`) no longer exists, and the model it describes is
+> not the one implemented. Kept for the business reasoning in it — the capacity
+> figures, the cost argument, the meeting decisions. For how the system actually
+> works read [CONTEXT.md](CONTEXT.md); for what is outstanding read
+> [ROADMAP.md](ROADMAP.md); for the original documents see
+> [docs/historico/](docs/historico/README.md).
+
 ---
 
 ## Por que este projeto existe