docs: translate the roadmap and frame it for an outside reader

roadmap.md is linked from the README table, so it is a page strangers land on.
Translated in full, with a note up front that none of it is a commitment:
there are no dates, the order is a recommendation, and an item can be dropped
once its plan is written. The note also points at product.md for the opposite
question — what the project deliberately will not do — so absence from the
roadmap is not read as a silent plan.

The model assigned to inbound-relay is dropped from the item; model routing
belongs in development.md, not in a statement of direction.

The README row described the file as internal and Russian. It is now neither.

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

README.md

@@ -37,7 +37,7 @@ send log and DNS checks in the panel, encrypted backups.
 | [Architecture](docs/architecture.md) | As-built technical design |
 | [Security](docs/security.md) | Accepted security trade-offs and requirements |
 | [Development](docs/development.md) | Building, testing, docs rules, model routing, commits |
-| [Roadmap](docs/roadmap.md) | Open work (1.x+) — internal, Russian |
+| [Roadmap](docs/roadmap.md) | Open work (1.x+) — direction, not commitments |
 | [CHANGELOG](CHANGELOG.md) | Release history |
 
 Repository: <https://github.com/mixeme/selfpost> — source, issues, releases, and