Refactor web build process and update documentation

- Removed Node.js build artifacts from .gitignore and adjusted Makefile to reflect changes in web UI build process, now using server-rendered Go templates instead of React.
- Updated README to clarify the new web UI architecture and output formats, emphasizing the removal of the Node.js build step.
- Added a command to set the number of frames per render task in manager configuration, enhancing user control over rendering settings.
- Improved Gitea workflow by removing unnecessary npm install step, streamlining the CI process.

internal/config/config.go

@@ -21,7 +21,8 @@ const (
 	KeyFixedAPIKey          = "fixed_api_key"
 	KeyRegistrationEnabled  = "registration_enabled"
 	KeyProductionMode       = "production_mode"
-	KeyAllowedOrigins       = "allowed_origins"
+	KeyAllowedOrigins        = "allowed_origins"
+	KeyFramesPerRenderTask  = "frames_per_render_task"
 )
 
 // Config manages application configuration stored in the database
@@ -301,3 +302,12 @@ func (c *Config) AllowedOrigins() string {
 	return c.GetWithDefault(KeyAllowedOrigins, "")
 }
 
+// GetFramesPerRenderTask returns how many frames to include per render task (min 1, default 1).
+func (c *Config) GetFramesPerRenderTask() int {
+	n := c.GetIntWithDefault(KeyFramesPerRenderTask, 1)
+	if n < 1 {
+		return 1
+	}
+	return n
+}
+