nav: refactor title rendering for flexibility

Updated navigation to use a custom title renderer for more flexible
rendering of navigation titles. This change decouples the rendering
logic from predefined formats, enabling dynamic title compositions
based on application context and data.

This includes:
- Refactoring `NavResponse` to introduce `NotedeckNavResponse` for
  handling unified navigation response data.
- Adding `NavTitle` in `ui/column/header.rs` to handle rendering
  of navigation titles and profile images dynamically.
- Updating route and timeline logic to support new rendering pipeline.
- Replacing hardcoded title rendering with data-driven approaches.

Benefits:
- Simplifies navigation handling by consolidating title and action
  management.
- Improves scalability for new navigation features without modifying
  core logic.
- Enhances visual customization capabilities.

Signed-off-by: William Casarin <jb55@jb55.com>

Cargo.toml

@@ -26,7 +26,7 @@ eframe = { workspace = true }
 egui_extras = { workspace = true }
 ehttp = "0.2.0"
 egui_tabs = { git = "https://github.com/damus-io/egui-tabs", branch = "egui-0.28" }
-egui_nav = { git = "https://github.com/damus-io/egui-nav", rev = "fd0900bdff4be35709372e921f2b49f68b261469" }
+egui_nav = { git = "https://github.com/damus-io/egui-nav", rev = "867fb6e057a4cc0a13716d59d6d332a4c90607ea" }
 egui_virtual_list = { git = "https://github.com/jb55/hello_egui", branch = "egui-0.28", package = "egui_virtual_list" }
 reqwest = { version = "0.12.4", default-features = false, features = [ "rustls-tls-native-roots" ] }
 image = { version = "0.25", features = ["jpeg", "png", "webp"] }