feat(i18n): add internationalization with DE, FR, ES, PT translations (#12)

Add a compile-time i18n system with 270 translation keys across 5 locales
(EN, DE, FR, ES, PT). Translations are embedded via include_str! and parsed
lazily into flat HashMaps with English fallback for missing keys.

- Add src/i18n module with Locale enum, t()/tw() lookup functions, and tests
- Add JSON translation files for all 5 locales under assets/i18n/
- Provide locale Signal via Dioxus context in App, persisted to localStorage
- Replace all hardcoded UI strings across 33 component/page files
- Add compact locale picker (globe icon + ISO alpha-2 code) in sidebar header
- Add click-outside backdrop dismissal for locale dropdown

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Co-authored-by: Sharang Parnerkar <parnerkarsharang@gmail.com>
Reviewed-on: #12

src/components/dashboard_sidebar.rs

@@ -1,5 +1,6 @@
 use dioxus::prelude::*;
 
+use crate::i18n::{t, Locale};
 use crate::infrastructure::ollama::{get_ollama_status, OllamaStatus};
 
 /// Right sidebar for the dashboard, showing Ollama status, trending topics,
@@ -21,6 +22,9 @@ pub fn DashboardSidebar(
     recent_searches: Vec<String>,
     on_topic_click: EventHandler<String>,
 ) -> Element {
+    let locale = use_context::<Signal<Locale>>();
+    let l = *locale.read();
+
     // Fetch Ollama status once on mount.
     // use_resource with no signal dependencies runs exactly once and
     // won't re-fire on parent re-renders (unlike use_effect).
@@ -50,14 +54,14 @@ pub fn DashboardSidebar(
 
             // -- Ollama Status Section --
             div { class: "sidebar-section",
-                h4 { class: "sidebar-section-title", "Ollama Status" }
+                h4 { class: "sidebar-section-title", "{t(l, \"dashboard.ollama_status\")}" }
                 div { class: "sidebar-status-row",
                     span { class: if current_status.online { "sidebar-status-dot sidebar-status-dot--online" } else { "sidebar-status-dot sidebar-status-dot--offline" } }
                     span { class: "sidebar-status-label",
                         if current_status.online {
-                            "Online"
+                            "{t(l, \"common.online\")}"
                         } else {
-                            "Offline"
+                            "{t(l, \"common.offline\")}"
                         }
                     }
                 }
@@ -73,7 +77,7 @@ pub fn DashboardSidebar(
             // -- Trending Topics Section --
             if !trending.is_empty() {
                 div { class: "sidebar-section",
-                    h4 { class: "sidebar-section-title", "Trending" }
+                    h4 { class: "sidebar-section-title", "{t(l, \"dashboard.trending\")}" }
                     for topic in trending.iter() {
                         {
                             let t = topic.clone();
@@ -92,7 +96,7 @@ pub fn DashboardSidebar(
             // -- Recent Searches Section --
             if !recent_searches.is_empty() {
                 div { class: "sidebar-section",
-                    h4 { class: "sidebar-section-title", "Recent Searches" }
+                    h4 { class: "sidebar-section-title", "{t(l, \"dashboard.recent_searches\")}" }
                     for search in recent_searches.iter() {
                         {
                             let s = search.clone();