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

shell/Caddyfile

@@ -0,0 +1,50 @@
+: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
+            }
+        }
+    }
+}