Translate docs to English, rewrite README, drop design handoff folder

Translate all of docs/ from Spanish to English and rewrite the root
README as a short project overview instead of a technical run guide.
Remove web-player/design_handoff_musify_player, an old design-tool
export that was no longer needed.

docs/README.md

@@ -1,47 +1,51 @@
-# Musify — Documentación
+# Musify documentation
 
-Musify es un backend de streaming de música: subir pistas, procesarlas (transcodificar el audio a `.m4a` y generar miniaturas), organizarlas en playlists y reproducirlas en streaming sin que los bytes pasen por la API.
+Musify is a music streaming backend: upload tracks, process them (transcode
+the audio to `.m4a`, generate thumbnails), organize them into playlists, and
+stream them without the bytes ever passing through the API.
 
-Esta carpeta explica **qué hace cada pieza, su propósito y por qué está diseñada así**.
+This folder explains **what each piece does, its purpose, and why it's built
+this way**.
 
-## Índice
+## Index
 
-- [architecture.md](architecture.md) — Visión global: componentes, cómo encajan y los flujos principales.
-- [projects.md](projects.md) — Qué es y para qué sirve cada proyecto/solución.
-- [authentication.md](authentication.md) — Zitadel (OIDC), validación de JWT, provisioning/sync de usuarios.
-- [storage.md](storage.md) — SeaweedFS (S3), estructura de claves, URLs prefirmadas, qué es público y qué privado.
-- [streaming.md](streaming.md) — Streaming del audio (`.m4a` por HTTP range) con stream-ticket (RS256) y el reverse proxy (StreamingGateway).
-- [media-processing.md](media-processing.md) — El worker y los workflows de MassTransit (transcode de audio, miniaturas).
-- [development.md](development.md) — Cómo levantar todo en local: contenedores, puertos y comandos.
-- [../deploy/README.md](../deploy/README.md) — El deploy en detalle: compose, scripts y producción.
+- [architecture.md](architecture.md): overview, components, how they fit together, and the main flows.
+- [projects.md](projects.md): what each project/solution is and what it's for.
+- [authentication.md](authentication.md): Zitadel (OIDC), JWT validation, user provisioning/sync.
+- [storage.md](storage.md): SeaweedFS (S3), key layout, presigned URLs, what's public vs. private.
+- [streaming.md](streaming.md): audio streaming (`.m4a` over HTTP range) with stream tickets (RS256) and the reverse proxy (StreamingGateway).
+- [media-processing.md](media-processing.md): the worker and its MassTransit workflows (audio transcoding, thumbnails).
+- [development.md](development.md): running everything locally, containers, ports, commands.
+- [../deploy/README.md](../deploy/README.md): deployment in detail, compose, scripts, and production.
 
-## Mapa de componentes (alto nivel)
+## Component map (high level)
 
 ```
                  ┌─────────────────────────────────────────────┐
-   Cliente  ───► │ Musify.Api (:5111)  API REST + emite tickets │
+   Client   ───► │ Musify.Api (:5111)  REST API + issues tickets│
                  └─────────────────────────────────────────────┘
-                        │ EF Core          │ presigned (subidas)   │ MassTransit (eventos)
+                        │ EF Core          │ presigned (uploads)   │ MassTransit (events)
                         ▼                  ▼                       ▼
-                 PostgreSQL          SeaweedFS S3 (:8333)     RabbitMQ ──► Worker (procesa)
-                 (metadatos)         (objetos)                            audio→.m4a, imágenes
+                 PostgreSQL          SeaweedFS S3 (:8333)     RabbitMQ ──► Worker (processes)
+                 (metadata)          (objects)                            audio→.m4a, images
                                           ▲
-   Cliente  ───► StreamingGateway (:8081) ┘   sirve audio .m4a (valida ticket, proxy al filer)
+   Client   ───► StreamingGateway (:8081) ┘   serves .m4a audio (validates ticket, proxies to the filer)
 
-   Login: Cliente ◄──► Zitadel (:8080, OIDC)   →  Musify.Api valida el JWT
+   Login: Client ◄──► Zitadel (:8080, OIDC)   →  Musify.Api validates the JWT
 ```
 
 ## Stack
 
 - **.NET 10**, C#. Minimal APIs (`Musify.Api`), Worker Service (`Musify.Worker`), ASP.NET + YARP (`Musify.StreamingGateway`).
-- **CQRS** con [Mediator] (source-generator) y resultados con **ErrorOr**.
-- **EF Core 10** + **PostgreSQL** (metadatos).
-- **MassTransit 8** + **RabbitMQ** (procesado asíncrono con routing slips/sagas).
-- **SeaweedFS** (almacenamiento de objetos compatible con S3, vía AWSSDK.S3).
-- **ffmpeg** (transcode de audio a AAC/`.m4a`), **SixLabors.ImageSharp** (miniaturas).
-- **Zitadel** (OIDC/OAuth2) para identidad.
+- **CQRS** with [Mediator] (source generator) and results via **ErrorOr**.
+- **EF Core 10** + **PostgreSQL** (metadata).
+- **MassTransit 8** + **RabbitMQ** (async processing with routing slips/sagas).
+- **SeaweedFS** (S3-compatible object storage, via AWSSDK.S3).
+- **ffmpeg** (audio transcoding to AAC/`.m4a`), **SixLabors.ImageSharp** (thumbnails).
+- **Zitadel** (OIDC/OAuth2) for identity.
 
-## Estructura del repositorio
+## Repository layout
 
-Un solo repo: `backend/` (los seis proyectos .NET), `web-player/` (cliente web
-SvelteKit), `deploy/` (stacks de Docker Compose y scripts) y `docs/`.
+A single repo: `backend/` (the six .NET projects), `web-player/` (the
+SvelteKit web client), `deploy/` (Docker Compose stacks and scripts), and
+`docs/`.