More monior TUI refactor/cleanup

`tui/tui.go` is no longer responsible for passing window resize updates
to all views, instead we request a new window size message to be sent at
the same time we enter the view, allowing the view to catch and handle
it.

Add `Initialized` to `tui/shared/View` model, now we only call
`Init` on a view before entering it for the first time, rather than
calling `Init` on all views when the application starts.

Renames file, small cleanups

pkg/tui/model/model.go

@@ -16,7 +16,6 @@ type LoadedConversation struct {
 	LastReply api.Message
 }
 
-// AppModel represents the application data model
 type AppModel struct {
 	Ctx           *lmcli.Context
 	Conversations []LoadedConversation
@@ -193,7 +192,6 @@ func (a *AppModel) PromptLLM(messages []api.Message, chatReplyChunks chan api.Ch
 	)
 }
 
-// Helper function
 func cycleSelectedMessage(selected *api.Message, choices []api.Message, dir MessageCycleDirection) (*api.Message, error) {
 	currentIndex := -1
 	for i, reply := range choices {