Add comprehensive documentation with i18n support (EN/BG)

- Add docs/ folder with English (en/) and Bulgarian (bg/) documentation
- Create index.md with language switching and links
- English docs: installation, quickstart, architecture, baraql, storage,
  schema, lsm, btree, vector, graph, fts, columnar, transactions,
  distributed, protocol, udf, api-binary, api-http, api-websocket
- Bulgarian docs: installation, quickstart, architecture, baraql,
  schema, lsm, btree, vector, graph, fts, transactions, distributed
- Update README license to BSD 3-Clause
- Add LICENSE file with BSD 3-Clause text

docs/en/api-http.md

@@ -0,0 +1,91 @@
+# HTTP/REST API
+
+JSON-based REST API for web applications.
+
+## Base URL
+
+```
+http://localhost:8080/api
+```
+
+## Endpoints
+
+### GET /api/users
+
+List all users:
+
+```bash
+curl http://localhost:8080/api/users
+```
+
+Response:
+```json
+[
+  {"id": 1, "name": "Alice", "age": 30},
+  {"id": 2, "name": "Bob", "age": 25}
+]
+```
+
+### GET /api/users/:id
+
+Get user by ID:
+
+```bash
+curl http://localhost:8080/api/users/1
+```
+
+### POST /api/users
+
+Create user:
+
+```bash
+curl -X POST http://localhost:8080/api/users \
+  -H "Content-Type: application/json" \
+  -d '{"name": "Charlie", "age": 35}'
+```
+
+### PUT /api/users/:id
+
+Update user:
+
+```bash
+curl -X PUT http://localhost:8080/api/users/1 \
+  -H "Content-Type: application/json" \
+  -d '{"name": "Alice", "age": 31}'
+```
+
+### DELETE /api/users/:id
+
+Delete user:
+
+```bash
+curl -X DELETE http://localhost:8080/api/users/1
+```
+
+## Query Endpoint
+
+Execute BaraQL queries via HTTP:
+
+```bash
+curl -X POST http://localhost:8080/api/query \
+  -H "Content-Type: application/json" \
+  -d '{"sql": "SELECT * FROM users WHERE age > 18"}'
+```
+
+## Error Response
+
+```json
+{
+  "error": {
+    "code": "INVALID_QUERY",
+    "message": "Syntax error at line 1"
+  }
+}
+```
+
+## Authentication
+
+```bash
+curl -H "Authorization: Bearer <token>" \
+  http://localhost:8080/api/users
+```