refactor: reorganize project structure and fix broken references

- Move scripts to scripts/ directory (roda.sh, prepara_db.py, etc.)
- Move shell config to shell/ directory (Caddyfile, auth.py, haloy.yml)
- Move basedosdados.duckdb to data/ directory
- Update Dockerfile and start.sh with new file paths
- Update README.md with correct script paths
- Remove Python ask.py (replaced by Rust binary in ask/ask)
- Add Rust source files (schema_filter.rs, sql_generator.rs, table_selector.rs)
- Remove sentence-transformer dependencies from ask
- Move docs and context artifacts to their directories

Caddyfile

@@ -1,50 +0,0 @@
-:8080 {
-    # Route based on Host header (set by haloy)
-    @ask {
-        host ask.xn--2dk.xyz
-    }
-    @db {
-        host db.xn--2dk.xyz
-    }
-
-    handle @ask {
-        reverse_proxy localhost:7682 {
-            flush_interval -1
-        }
-    }
-
-    handle @db {
-        handle /health {
-            respond 200
-        }
-
-        handle /login {
-            reverse_proxy 127.0.0.1:8081
-        }
-
-        handle /query {
-            reverse_proxy 127.0.0.1:8081
-        }
-
-        @websocket {
-            header Connection *Upgrade*
-            header Upgrade websocket
-        }
-
-        handle @websocket {
-            reverse_proxy localhost:7681 {
-                flush_interval -1
-            }
-        }
-
-        handle {
-            forward_auth 127.0.0.1:8081 {
-                uri /auth
-                copy_headers Cookie
-            }
-            reverse_proxy localhost:7681 {
-                flush_interval -1
-            }
-        }
-    }
-}