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/app.rs

@@ -52,6 +52,9 @@ pub struct Damus {
     pub since_optimize: bool,
     pub textmode: bool,
 
+    /// Scramble text for development
+    pub scramble: bool,
+
     pub unrecognized_args: BTreeSet<String>,
 }
 
@@ -430,6 +433,7 @@ impl Damus {
             drafts: Drafts::default(),
             state: DamusState::Initializing,
             textmode: parsed_args.textmode,
+            scramble: parsed_args.scramble,
             //frame_history: FrameHistory::default(),
             view_state: ViewState::default(),
             tmp_columns,
@@ -474,6 +478,7 @@ impl Damus {
             drafts: Drafts::default(),
             state: DamusState::Initializing,
             textmode: false,
+            scramble: false,
             tmp_columns: true,
             //frame_history: FrameHistory::default(),
             view_state: ViewState::default(),