feat(i18n): French and German localization (phase 5)

- Add full message catalogs and content for French (fr) and German (de)
- Implement ASCII canonical slugs for French and German routes
- Add language-specific search endpoints (/api/busca/fr, /api/busca/de)
- Configure strict 404 responses for /fr/livro and /de/livro
- Localize SEO, OpenGraph (fr_FR, de_DE), Twitter and JSON-LD schemas
- Add localized code example comments across 14 examples for fr and de
- Enable 'fr' and 'de' in ENABLED_LOCALES with root negotiation and redirect
- Extend test suite in check-i18n, smoke-imagem and verifica-vazamentos

Co-Authored-By: Antigravity <noreply@google.com>

public/exemplos/fr/rust-esp.rs

@@ -0,0 +1,48 @@
+//! Exemplo Rust no ESP32 usando `esp-hal` (Modo Bare-Metal / no_std)
+//! Pisca um LED e envia mensagens via UART Serial com segurança de memória garantida.
+//!
+//! Cargo.toml:
+//!   esp-hal = { version = "0.22", features = ["esp32s3"] }
+//!   esp-println = { version = "0.12", features = ["esp32s3", "log"] }
+
+#![no_std]
+#![no_main]
+
+use esp_backtrace as _;
+use esp_hal::{
+    clock::ClockControl,
+    gpio::{Io, Level, Output},
+    peripherals::Peripherals,
+    system::SystemControl,
+    timer::timg::TimerGroup,
+    delay::Delay,
+    prelude::*,
+};
+use esp_println::println;
+
+#[entry]
+fn main() -> ! {
+    // Inicializa periféricos do SoC com verificação em tempo de compilação
+    let peripherals = Peripherals::take();
+    let system = SystemControl::new(peripherals.SYSTEM);
+    let clocks = ClockControl::boot_defaults(system.clock_control).freeze();
+
+    // Configura os pinos de E/S
+    let io = Io::new(peripherals.GPIO, peripherals.IO_MUX);
+    let mut led = Output::new(io.pins.gpio2, Level::Low);
+
+    let delay = Delay::new(&clocks);
+
+    println!("🦀 Firmware Rust Bare-Metal inicializado no ESP32!");
+
+    let mut counter: u32 = 0;
+
+    loop {
+        // Inverte estado do LED com garantia de exclusão mútua
+        led.toggle();
+        counter += 1;
+
+        println!("Ciclo Rust #{}: LED está {:?}", counter, led.is_set_high());
+        delay.delay_millis(500);
+    }
+}