Track the editor config, local Claude permissions and the maintenance scripts

.editorconfig fixes indentation and line endings for every editor. The
scripts/ helpers (database import checks, the monolith guard, and the two
refactor migrations) were only ever local.

.editorconfig

@@ -0,0 +1,12 @@
+root = true
+
+[*]
+indent_style = space
+indent_size = 4
+charset = utf-8
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[*.md]
+trim_trailing_whitespace = false