docs: tambah doc comment, logging, dan inline comments di semua 255 file

Meliputi:
- File-level //! doc comment: tujuan file, alur kerja, komponen utama
- Function-level /// doc comment: apa, parameter, return, flow, edge cases
- Struct/enum/trait /// doc comment: peran, field docs
- Tracing logging (tracing::info!/debug!/trace!/warn!/error!) di setiap fungsi
- Inline comments untuk variable dan branching logic penting
- Seluruh 8 crates di workspace: zesdex-backend, zesdex-cms, zesdex-entities,
  zesdex-iam, zesdex-infra, zesdex-ipc, zesdex-middleware, zesdex-utils
- Build: 0 errors, 242/242 tests passed

crates/zesdex-backend/src/app/mode/settings.rs

@@ -3,6 +3,7 @@
 //! Flow: exposes small mutation functions (currently just cycling the
 //! internet access mode) invoked by keybindings while the settings overlay
 //! is active.
+use tracing::debug;
 use zesdex_cms::domain::settings::{InternetMode, Settings};
 
 /// Advance the internet access mode to the next value in the cycle.
@@ -14,9 +15,11 @@ use zesdex_cms::domain::settings::{InternetMode, Settings};
 ///
 /// Return: nothing; mutates `settings.internet_mode` in place.
 pub fn cycle_internet_mode(settings: &mut Settings) {
+    let before = settings.internet_mode.clone();
     settings.internet_mode = match settings.internet_mode {
         InternetMode::Off => InternetMode::ReadOnly,
         InternetMode::ReadOnly => InternetMode::Full,
         InternetMode::Full => InternetMode::Off,
     };
+    debug!(?before, ?settings.internet_mode, "cycle_internet_mode");
 }