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>

Cargo.lock

@@ -870,6 +870,61 @@ dependencies = [
  "arrayvec 0.7.6",
 ]
 
+[[package]]
+name = "axum"
+version = "0.7.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "edca88bc138befd0323b20752846e6587272d3b03b0343c8ea28a6f819e6e71f"
+dependencies = [
+ "async-trait",
+ "axum-core",
+ "bytes",
+ "futures-util",
+ "http",
+ "http-body",
+ "http-body-util",
+ "hyper",
+ "hyper-util",
+ "itoa",
+ "matchit",
+ "memchr",
+ "mime",
+ "percent-encoding",
+ "pin-project-lite",
+ "rustversion",
+ "serde",
+ "serde_json",
+ "serde_path_to_error",
+ "serde_urlencoded",
+ "sync_wrapper",
+ "tokio",
+ "tower",
+ "tower-layer",
+ "tower-service",
+ "tracing",
+]
+
+[[package]]
+name = "axum-core"
+version = "0.4.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "09f2bd6146b97ae3359fa0cc6d6b376d9539582c7b4220f041a33ec24c226199"
+dependencies = [
+ "async-trait",
+ "bytes",
+ "futures-util",
+ "http",
+ "http-body",
+ "http-body-util",
+ "mime",
+ "pin-project-lite",
+ "rustversion",
+ "sync_wrapper",
+ "tower-layer",
+ "tower-service",
+ "tracing",
+]
+
 [[package]]
 name = "backtrace"
 version = "0.3.76"
@@ -2248,6 +2303,26 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "cosmobiologia-server"
+version = "0.1.0"
+dependencies = [
+ "axum",
+ "clap",
+ "cosmobiologia-engine",
+ "cosmobiologia-model",
+ "cosmobiologia-render",
+ "cosmobiologia-store",
+ "directories",
+ "serde",
+ "serde_json",
+ "thiserror 2.0.18",
+ "tokio",
+ "tower-http",
+ "tracing",
+ "tracing-subscriber",
+]
+
 [[package]]
 name = "cosmobiologia-store"
 version = "0.1.0"
@@ -4917,12 +4992,24 @@ dependencies = [
  "pin-project-lite",
 ]
 
+[[package]]
+name = "http-range-header"
+version = "0.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9171a2ea8a68358193d15dd5d70c1c10a2afc3e7e4c5bc92bc9f025cebd7359c"
+
 [[package]]
 name = "httparse"
 version = "1.10.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6dbf3de79e51f3d586ab4cb9d5c3e2c14aa28ed23d180cf89b4df0454a69cc87"
 
+[[package]]
+name = "httpdate"
+version = "1.0.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "df3b46402a9d5adb4c86a0cf463f42e19994e3ee891101b1841f30a545cb49a9"
+
 [[package]]
 name = "humantime"
 version = "2.3.0"
@@ -4943,6 +5030,7 @@ dependencies = [
  "http",
  "http-body",
  "httparse",
+ "httpdate",
  "itoa",
  "pin-project-lite",
  "smallvec",
@@ -6571,6 +6659,12 @@ dependencies = [
  "regex-automata",
 ]
 
+[[package]]
+name = "matchit"
+version = "0.7.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0e7465ac9959cc2b1404e8e2367b43684a6d13790fe23056cc8c6c5a6b7bcb94"
+
 [[package]]
 name = "matrixmultiply"
 version = "0.3.10"
@@ -9955,6 +10049,17 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "serde_path_to_error"
+version = "0.1.20"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "10a9ff822e371bb5403e391ecd83e182e0e77ba7f6fe0160b795797109d1b457"
+dependencies = [
+ "itoa",
+ "serde",
+ "serde_core",
+]
+
 [[package]]
 name = "serde_repr"
 version = "0.1.20"
@@ -11551,6 +11656,7 @@ dependencies = [
  "tokio",
  "tower-layer",
  "tower-service",
+ "tracing",
 ]
 
 [[package]]
@@ -11561,13 +11667,23 @@ checksum = "68d6fdd9f81c2819c9a8b0e0cd91660e7746a8e6ea2ba7c6b2b057985f6bcb51"
 dependencies = [
  "bitflags 2.11.1",
  "bytes",
+ "futures-core",
  "futures-util",
  "http",
  "http-body",
+ "http-body-util",
+ "http-range-header",
+ "httpdate",
+ "mime",
+ "mime_guess",
+ "percent-encoding",
  "pin-project-lite",
+ "tokio",
+ "tokio-util",
  "tower",
  "tower-layer",
  "tower-service",
+ "tracing",
  "url",
 ]
 
@@ -11589,6 +11705,7 @@ version = "0.1.44"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "63e71662fa4b2a2c3a26f570f037eb95bb1f85397f3cd8076caed2f026a6d100"
 dependencies = [
+ "log",
  "pin-project-lite",
  "tracing-attributes",
  "tracing-core",