feat(i18n): implement translations for block creation window and units

- Localize block description placeholder via BlockDefinitionState field
- Add lookup mappings to locale_catalog for block definition dialog,
  validation messages, on-screen prompts, and insertion units
- Add Fluent strings for all 41 keys across all 21 supported locales

src/locale_catalog.rs

@@ -5178,6 +5178,47 @@ pub(super) fn message_attribute(source: &str) -> Option<(&'static str, &'static
         "Mid Between 2 Points" => Some(("ui", "mid-between-2-points")),
         "Osnap Settings..." => Some(("ui", "osnap-settings")),
         "Snap override: None (next pick only)." => Some(("ui", "snap-override-none-next-pick-only")),
+        "Allow exploding" => Some(("common", "allow-exploding")),
+        "Angstroms" => Some(("common", "angstroms")),
+        "Astronomical Units" => Some(("common", "astronomical-units")),
+        "BLOCK  Select objects:" => Some(("insert", "block-select-objects")),
+        "BLOCK  Specify insertion base point:" => Some(("insert", "block-specify-insertion-base-point")),
+        "BLOCK creates a block definition from objects you select." => Some(("common", "block-creates-a-block-definition-from-objects-you-select")),
+        "Behavior" => Some(("common", "behavior")),
+        "Block \"{name}\" already exists.\nDo you want to redefine it?" => Some(("common", "block-name-already-exists-do-you-want-to-redefine-it")),
+        "Block \"{}\" already exists — will redefine upon OK" => Some(("common", "block-already-exists-will-redefine-upon-ok")),
+        "Block Definition" => Some(("common", "block-definition")),
+        "Block name" => Some(("common", "block-name")),
+        "Block name cannot be empty." => Some(("common", "block-name-cannot-be-empty")),
+        "Block name cannot contain: \\ / : * ? \" < > | = `" => Some(("common", "block-name-cannot-contain-invalid-chars")),
+        "Block name cannot start with '*'." => Some(("common", "block-name-cannot-start-with-star")),
+        "Block unit:" => Some(("common", "block-unit-label")),
+        "Convert to block" => Some(("common", "convert-to-block")),
+        "Decameters" => Some(("common", "decameters")),
+        "Decimeters" => Some(("common", "decimeters")),
+        "Enter block description..." => Some(("common", "enter-block-description")),
+        "Gigameters" => Some(("common", "gigameters")),
+        "Hectometers" => Some(("common", "hectometers")),
+        "Hyperlink*" => Some(("common", "hyperlink-star")),
+        "Hyperlink..." => Some(("common", "hyperlink-ellipsis")),
+        "Invalid character '{invalid_char}' in block name (\\ / : * ? \" < > | = ` are not allowed)" => Some(("common", "invalid-character-in-block-name")),
+        "Light Years" => Some(("common", "light-years")),
+        "Match block orientation" => Some(("common", "match-block-orientation")),
+        "Microinches" => Some(("common", "microinches")),
+        "Microns" => Some(("common", "microns")),
+        "Mils" => Some(("common", "mils")),
+        "Nanometers" => Some(("common", "nanometers")),
+        "No objects selected" => Some(("common", "no-objects-selected")),
+        "No objects selected. You must select objects to define a block." => Some(("common", "no-objects-selected-you-must-select-objects-to-define-a-block")),
+        "Objects" => Some(("common", "objects-title-case")),
+        "Parsecs" => Some(("common", "parsecs")),
+        "Pick point" => Some(("common", "pick-point")),
+        "Retain" => Some(("common", "retain")),
+        "Scale uniformly" => Some(("common", "scale-uniformly")),
+        "Specify On-screen" => Some(("common", "specify-on-screen")),
+        "US Survey Feet" => Some(("common", "us-survey-feet")),
+        "to layout" => Some(("common", "to-layout")),
+        "{count} objects selected" => Some(("common", "count-objects-selected")),
         _ => None,
     }
 }

src/ui/window/block_definition.rs

@@ -72,6 +72,7 @@ pub struct BlockDefinitionState {
     pub hyperlink_desc: String,
     pub error_message: Option<String>,
     pub confirm_redefine: Option<String>,
+    pub desc_placeholder: String,
 }
 
 impl Clone for BlockDefinitionState {
@@ -98,6 +99,7 @@ impl Clone for BlockDefinitionState {
             hyperlink_desc: self.hyperlink_desc.clone(),
             error_message: self.error_message.clone(),
             confirm_redefine: self.confirm_redefine.clone(),
+            desc_placeholder: self.desc_placeholder.clone(),
         }
     }
 }
@@ -126,6 +128,7 @@ impl BlockDefinitionState {
             hyperlink_desc: String::new(),
             error_message: None,
             confirm_redefine: None,
+            desc_placeholder: crate::t!("Enter block description...").into_owned(),
         }
     }
 
@@ -532,7 +535,7 @@ pub fn view_window<'a>(
     // ── Group: Description (Column 2 Bottom) ──────────────────────────────────
     let desc_editor = text_editor(&state.description_content)
         .on_action(Message::BlockDefDescriptionAction)
-        .placeholder("Enter block description...")
+        .placeholder(&state.desc_placeholder)
         .size(11)
         .padding([4, 6])
         .height(Fill)