feat(insert): add docked block palette

Add a searchable block palette with previews, file import, collision-safe nested definitions, and dependency/table-record import. Keep palette thumbnails current across drawing switches and block-definition edits.

src/ui/command_line.rs

@@ -910,6 +910,7 @@ fn history_highlight_format(
 #[cfg(test)]
 mod tests {
     use super::{ranked_matches, CommandLine};
+    use crate::t;
     use rustc_hash::FxHashMap;
 
     fn aliases(pairs: &[(&str, &str)]) -> FxHashMap<String, String> {