Trim whitespace on terminal copy by default, keep raw copy on Ctrl+Shift+Alt+C and right-click menu

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

app/src/components/terminal/trimSelection.ts

@@ -0,0 +1,42 @@
+/**
+ * Cleans up terminal selections for pasting into other tools.
+ *
+ * Terminal UI padding (left margin from the xterm container, alignment spaces
+ * at end of line) ends up in the copied text. This helper removes that cruft
+ * while preserving the *relative* indentation of the content — so code blocks
+ * keep their shape but lose the wrapper padding.
+ *
+ * Steps:
+ *   1. Dedent — strip the common leading whitespace count from every line.
+ *   2. trimEnd — drop trailing whitespace per line.
+ *   3. Drop fully-blank leading and trailing lines.
+ *
+ * Internal newlines and relative indentation are preserved. Pure function.
+ */
+export function trimSelection(text: string): string {
+  if (!text) return text;
+
+  const lines = text.split("\n");
+
+  let minIndent = Infinity;
+  for (const line of lines) {
+    if (line.trim() === "") continue;
+    const match = line.match(/^[ \t]*/);
+    const indent = match ? match[0].length : 0;
+    if (indent < minIndent) minIndent = indent;
+    if (minIndent === 0) break;
+  }
+  if (!Number.isFinite(minIndent)) minIndent = 0;
+
+  const processed = lines.map((line) => {
+    const afterDedent = line.length >= minIndent ? line.slice(minIndent) : "";
+    return afterDedent.trimEnd();
+  });
+
+  let start = 0;
+  let end = processed.length;
+  while (start < end && processed[start] === "") start++;
+  while (end > start && processed[end - 1] === "") end--;
+
+  return processed.slice(start, end).join("\n");
+}