feat: funciones Python infra y tipos Python (core, datascience, infra)

Infra: cache_to_file, cache_to_sqlite, http_download_file, http_get_json,
http_post_json, read_file_with_encoding, safe_extract_zip, scan_directory,
setup_logger, normalize_zip_filenames.
Tipos: 30+ tipos core (agent_action, context, task, message, parse_result...),
6 tipos datascience (entity_candidate, extraction_result...), 2 tipos infra.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

python/functions/infra/http_post_json.md

@@ -0,0 +1,40 @@
+---
+name: http_post_json
+kind: function
+lang: py
+domain: infra
+version: "1.0.0"
+purity: impure
+signature: "http_post_json(url: str, body: dict, headers: dict[str, str] | None = None, timeout: float = 30.0) -> dict"
+description: "POST request con body JSON. Agrega Content-Type: application/json y Accept: application/json. Lanza RuntimeError si status >= 400 con status code, url truncada y primeros 200 chars del body."
+tags: [http, json, post, client, network, stdlib, infra]
+uses_functions: []
+uses_types: []
+returns: []
+returns_optional: false
+error_type: "error_go_core"
+imports: ["json", "urllib.error", "urllib.request"]
+tested: true
+tests:
+  - "mock de POST con body serializado correctamente"
+  - "mock de respuesta 201"
+  - "mock de respuesta 500 → error"
+  - "body con unicode"
+test_file_path: "python/functions/infra/http_post_json_test.py"
+file_path: "python/functions/infra/http_post_json.py"
+---
+
+## Ejemplo
+
+```python
+response = http_post_json(
+    "https://api.example.com/users",
+    body={"name": "Alice", "role": "admin"},
+    headers={"X-Api-Key": "secret"},
+)
+print(response["id"])
+```
+
+## Notas
+
+Solo usa stdlib (urllib). El body se serializa con json.dumps(ensure_ascii=False) y se codifica a UTF-8. Headers custom se fusionan con Content-Type y Accept por defecto (los custom tienen precedencia).