chore(i18n): finish translating code comments and scripts to English

Completes the English-only standardization for code, comments, scripts
and CI templates (UI/CLI-facing strings stay bilingual pt-BR/en,
untouched). Covers the remaining crates/, apps/gui/ui/ and
apps/gui/src-tauri/ comments, .gitea/ workflow and template comments,
.githooks/ hooks, and the scripts/ source comments for the files
already renamed in a prior commit (check.sh, generate-logo.py,
install-hooks.sh).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VAyr8d7HuAdUGB6aA5xmDD

crates/guara-core/tests/jpegscan.rs

@@ -1,7 +1,7 @@
 use guara_core::jpegscan::*;
 
 fn photo(w: u16, h: u16) -> Vec<u8> {
-    // Imagem "natural": gradientes suaves + textura + bordas.
+    // Synthetic natural-looking test image: smooth gradients + texture + geometric edges.
     let mut rgb = Vec::with_capacity(w as usize * h as usize * 3);
     let mut x = 0x9E3779B97F4A7C15u64;
     for yy in 0..h as i32 {
@@ -35,7 +35,7 @@ fn decodes_whole_image_and_ends_at_eoi() {
     let d = decode(&h, &j, State::start(&h), u32::MAX, 0);
     assert_eq!(d.stop, Stop::Done);
     assert_eq!(d.dc.len() as u32, h.total_mcus());
-    // O que sobra depois do último MCU é o EOI.
+    // Only the 2-byte EOI marker (`FF D9`) remains after decoding all MCUs.
     let tail = &j[d.state.pos.min(j.len())..];
     assert!(
         tail.windows(2).any(|w| w == [0xFF, 0xD9]),
@@ -48,9 +48,9 @@ fn decodes_whole_image_and_ends_at_eoi() {
 fn detects_break_and_resumes_with_the_right_continuation() {
     let j = photo(1024, 768);
     let h = parse_header(&j).unwrap();
-    let cut = 12 * 4096; // quebra no limite de cluster
+    let cut = 12 * 4096; // simulate a fragmentation break on a 4 KiB cluster boundary
     assert!(j.len() > cut + 8192, "imagem pequena demais: {}", j.len());
-    // Dados estranhos no lugar do resto.
+    // Splice foreign pseudo-random bytes (without `0xFF` markers) after the cut point.
     let mut x = 12345u64;
     let junk: Vec<u8> = (0..40_000)
         .map(|_| {
@@ -64,16 +64,16 @@ fn detects_break_and_resumes_with_the_right_continuation() {
     broken.extend_from_slice(&junk);
     let d = decode(&h, &broken, State::start(&h), u32::MAX, 512);
     assert_ne!(d.stop, Stop::Done);
-    // Decodificação segue o lixo por um tempo; mas a quebra aparece pelo erro ou pela descontinuidade.
+    // Decoding continues into the foreign cluster briefly, then triggers a Huffman error or DC jump.
     let mcu_break = first_discontinuity(&h, &d.dc);
-    // MCUs bons: os decodificados ao fim do cluster `cut`.
+    // Last valid checkpoint at the end of the first fragment (`cut`).
     let good = d
         .snaps
         .iter()
         .rfind(|s| s.pos <= cut)
         .expect("snapshot antes da quebra")
         .clone();
-    // Retomada com a continuação verdadeira reproduz a decodificação inteira.
+    // Resuming from that checkpoint with the true second fragment reconstructs the entire image.
     let mut joined = j[..cut].to_vec();
     joined.extend_from_slice(&j[cut..]);
     let r = decode(&h, &joined, good.clone(), u32::MAX, 0);