feat: config settings grouped under ui, values, storage and providers

icons, sourcesView, collapseGroups, loadDelay and expiryWarningDays move
under ui; revealTimeout, hideOnBlur and clipboardClear under values;
cache and history under storage; timeout under providers. share is now
sharing, in the config and in a repo's .lazysecrets.yaml.

internal/ui/app/usage.go

@@ -8,7 +8,7 @@ import (
 // Usage: revealing, copying, opening in the browser, sharing and jumping
 // to an item count as using it. The store keeps when each item was last
 // used and how often, for the Recent section of the jump list. The config's
-// history: false turns this off.
+// storage.history: false turns this off.
 
 // used counts a use of the remembered item key, keeping its context.
 func (m *Model) used(key string) {