feat(api): enhance image module management and export functionality

- Added read-write access to the darktable SQLite catalog for module parameter edits.
- Implemented new endpoints for exporting images and retrieving full-resolution images.
- Introduced PATCH method for updating module parameters with optional preview.
- Added comprehensive tests for new API functionalities, including module retrieval and error handling.
- Updated CORS headers to support new HTTP methods.
- Created detailed documentation for new API endpoints and module operations.

contrib/darktable-api/router.lua

@@ -29,9 +29,10 @@ local function register(method, pattern, handler)
   routes[#routes+1] = { method = method:upper(), parts = compile(pattern), handler = handler }
 end
 
-function M.get(pattern, handler)  register("GET",  pattern, handler) end
-function M.post(pattern, handler) register("POST", pattern, handler) end
-function M.put(pattern, handler)  register("PUT",  pattern, handler) end
+function M.get(pattern, handler)    register("GET",    pattern, handler) end
+function M.post(pattern, handler)   register("POST",   pattern, handler) end
+function M.put(pattern, handler)    register("PUT",    pattern, handler) end
+function M.patch(pattern, handler)  register("PATCH",  pattern, handler) end
 function M.delete(pattern, handler) register("DELETE", pattern, handler) end
 
 -- Match a request against registered routes.