feat(cosmobiologia-server): server HTTP single-user con CRUD completo (fase 2)

Crate nuevo `cosmobiologia-server` (binario axum, nativo) que
monta `cosmobiologia-engine` + `cosmobiologia-store` y expone
la rueda + el CRUD del tree por HTTP.

Endpoints v1:
- `GET  /api/health`
- `GET  /api/tree`                         tree completo anidado
- `POST /api/groups`                       crear grupo
- `PATCH /api/groups/:id`                  renombrar
- `DELETE /api/groups/:id`                 borrar
- `POST /api/contacts`                     crear contacto
- `PATCH /api/contacts/:id`                renombrar
- `DELETE /api/contacts/:id`               borrar
- `POST /api/charts`                       crear carta
- `GET  /api/charts/:id`                   chart JSON
- `PATCH /api/charts/:id`                  editar (label/birth/config)
- `DELETE /api/charts/:id`                 borrar
- `GET  /api/charts/:id/render`            RenderModel JSON
- `GET  /api/charts/:id/svg`               SVG inline (reusa
                                            svg_export del engine)
- `GET  /api/sky`                          "Cielo ahora" — RenderModel
                                            UTC actual sin chart_id real

Query params del render para activar overlays sin POST:
- `offset_min=<i64>`                       time scrubbing
- `transit=1`                              overlay de tránsito al now
- `prog_age=<f64>`                         progresión secundaria
- `sa_age=<f64>`                           solar arc
- `pd_age=<f64>`                           primary directions (Naibod)

Decisiones:
- Single-user, sin auth. Bind por default a `127.0.0.1:8787` —
  el server NO debe exponerse a la red pública en esta fase.
- DB por default = misma del desktop (`$XDG_DATA_HOME/cosmobiologia/
  charts.db`). `--db` permite override.
- CORS permissive (es localhost, single-user, sin auth).
- `ApiError` con mapeo a HTTP status: 404 NotFound,
  400 BadRequest, 500 todo lo demás. Body JSON `{ "error": "..." }`.

Smoke test:
  cargo run -p cosmobiologia-server -- --port 18787
  curl /api/health         → {"status":"ok",...}
  curl POST /api/groups    → {"id":"01KRYVP...","name":"Familia",...}
  curl POST /api/contacts  → {"id":"01KRYVP...","group_id":...}
  curl /api/tree           → árbol anidado
  curl /api/sky            → RenderModel con VSOP real

Pendiente (fase 3): cliente `cosmobiologia-web` (cdylib WASM)
que consuma estos endpoints y pinte SVG/Canvas2D.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

crates/apps/cosmobiologia-server/Cargo.toml

@@ -0,0 +1,27 @@
+[package]
+name = "cosmobiologia-server"
+version = { workspace = true }
+edition = { workspace = true }
+license = { workspace = true }
+description = "Cosmobiología — server HTTP single-user. axum + cosmobiologia-engine. Sirve cartas y assets del cliente web. CRUD completo de groups/contacts/charts."
+
+[dependencies]
+cosmobiologia-engine = { path = "../../modules/cosmobiologia/cosmobiologia-engine" }
+cosmobiologia-model = { path = "../../modules/cosmobiologia/cosmobiologia-model" }
+cosmobiologia-render = { path = "../../modules/cosmobiologia/cosmobiologia-render" }
+cosmobiologia-store = { path = "../../modules/cosmobiologia/cosmobiologia-store" }
+
+tokio = { workspace = true }
+serde = { workspace = true }
+serde_json = { workspace = true }
+thiserror = { workspace = true }
+tracing = { workspace = true }
+tracing-subscriber = { workspace = true }
+directories = { workspace = true }
+clap = { version = "4", features = ["derive"] }
+axum = "0.7"
+tower-http = { version = "0.6", features = ["cors", "trace", "fs"] }
+
+[[bin]]
+name = "cosmobiologia-server"
+path = "src/main.rs"