Make remember tool instructions more imperative in system prompts

- Change 'call remember' to 'you MUST call remember' in native prompt
- Change 'IF you discovered' to 'ALWAYS...when you discovered'
- Add explicit list of trigger tools (code_search, rg, grep, find, read_file)
- Add reminder to Response Guidelines section
- Add remember tool and Project Memory section to non-native prompt
- Remove redundant console output from remember tool
- Fix test compilation errors (missing summary parameter, temporary borrow)

crates/g3-core/src/tools/memory.rs

@@ -68,9 +68,6 @@ pub async fn execute_remember<W: UiWriter>(
     // Write back
     std::fs::write(&memory_path, &final_content)?;
 
-    ctx.ui_writer
-        .println(&format!("💾 Memory updated ({})", format_size(final_content.len())));
-
     Ok(format!("Memory updated. Size: {}", format_size(final_content.len())))
 }