feat: add scramble flag for development text scrambling

This commit introduces a new scramble option to help reduce distractions
during development by scrambling text using rot13. When enabled via the
new `--scramble` flag, text displayed in various views is transformed,
making it easier to focus on layout and behavior without reading the
actual content.

App & Args Updates

  - Added a `scramble: bool` field to the main application state (in `app.rs`).

  - Extended argument parsing (in `args.rs`) to recognize the `--scramble` flag.

NoteOptions Enhancement

  - Introduced a new bit flag `scramble_text` in `NoteOptions` with
    corresponding setter/getter methods.

UI Adjustments

  - Propagated the scramble flag through note rendering functions across
    navigation, timeline, and note view modules.

  - Updated several UI components (e.g., in `nav.rs`, `route.rs`, and
    `contents.rs`) to accept and apply the new note options.

Rot13 Implementation

  - Implemented a helper function (`rot13`) to scramble text
    conditionally when the scramble option is enabled.

This feature is intended for development builds only, offering a way to
obscure text content during UI tweaks and testing.

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

crates/notedeck_columns/src/ui/note/options.rs

@@ -15,6 +15,9 @@ bitflags! {
         const textmode        = 0b0000000001000000;
         const options_button  = 0b0000000010000000;
         const hide_media      = 0b0000000100000000;
+
+        /// Scramble text so that its not distracting during development
+        const scramble_text   = 0b0000001000000000;
     }
 }
 
@@ -52,6 +55,7 @@ impl NoteOptions {
     create_bit_methods!(set_wide, has_wide, wide);
     create_bit_methods!(set_options_button, has_options_button, options_button);
     create_bit_methods!(set_hide_media, has_hide_media, hide_media);
+    create_bit_methods!(set_scramble_text, has_scramble_text, scramble_text);
 
     pub fn new(is_universe_timeline: bool) -> Self {
         let mut options = NoteOptions::default();