Display raw PGP signature in verification dialog

Modified the verify_note_signature() function to show the complete raw PGP
signature text when users press 'V' in the note details view. This allows
users to copy/paste signatures into external tools like Kleopatra for
independent verification.

Changes:
- Added raw signature display after verification status info
- Implemented scrollable dialog with arrow keys and Page Up/Down support
- Added clear separator and label for the signature section
- Shows signature for verified, failed, and unsigned notes (when present)

Users can now easily copy PGP signatures for external verification workflows.

trace/tui_app.py

@@ -119,7 +119,7 @@ class TUI:
         self.flash_time = time.time()
 
     def verify_note_signature(self):
-        """Show detailed verification dialog for current note"""
+        """Show detailed verification dialog for current note with raw signature"""
         if not self.current_note:
             return
 
@@ -134,6 +134,7 @@ class TUI:
                 "To sign notes, enable GPG signing in settings",
                 "and ensure you have a GPG key configured."
             ]
+            signature_lines = []
         elif verified:
             title = "✓ Signature Verified"
             message = [
@@ -141,8 +142,13 @@ class TUI:
                 "",
                 f"Signed by: {info}",
                 "",
-                "This note has not been tampered with since signing."
+                "This note has not been tampered with since signing.",
+                "",
+                "─" * 60,
+                "RAW PGP SIGNATURE (copy/paste for external verification):",
+                "─" * 60,
             ]
+            signature_lines = self.current_note.signature.split('\n')
         else:
             title = "✗ Signature Verification Failed"
             message = [
@@ -153,37 +159,79 @@ class TUI:
                 "Possible causes:",
                 "- Public key not in keyring",
                 "- Note content was modified after signing",
-                "- Signature is corrupted"
+                "- Signature is corrupted",
+                "",
+                "─" * 60,
+                "RAW PGP SIGNATURE (copy/paste for external verification):",
+                "─" * 60,
             ]
+            signature_lines = self.current_note.signature.split('\n')
 
-        # Display dialog (reuse pattern from other dialogs)
+        # Combine message and signature
+        all_lines = message + signature_lines
+
+        # Display scrollable dialog
         h, w = self.stdscr.getmaxyx()
-        dialog_h = min(len(message) + 6, h - 4)
+        dialog_h = min(h - 4, 40)  # Max height for dialog
-        dialog_w = min(max(len(line) for line in [title] + message) + 6, w - 4)
+        dialog_w = min(w - 4, 100)  # Max width for dialog
         start_y = (h - dialog_h) // 2
         start_x = (w - dialog_w) // 2
 
         # Create dialog window
         dialog = curses.newwin(dialog_h, dialog_w, start_y, start_x)
-        dialog.box()
 
-        # Title
+        scroll_offset = 0
-        dialog.attron(curses.A_BOLD)
+        max_scroll = max(0, len(all_lines) - (dialog_h - 6))
-        title_x = (dialog_w - len(title)) // 2
-        dialog.addstr(1, title_x, title)
-        dialog.attroff(curses.A_BOLD)
 
-        # Message
+        while True:
-        for i, line in enumerate(message):
+            dialog.clear()
-            dialog.addstr(3 + i, 2, line)
+            dialog.box()
 
-        # Footer
+            # Title
-        footer = "Press any key to close"
+            dialog.attron(curses.A_BOLD)
-        footer_x = (dialog_w - len(footer)) // 2
+            title_x = (dialog_w - len(title)) // 2
-        dialog.addstr(dialog_h - 2, footer_x, footer, curses.color_pair(3))
+            try:
+                dialog.addstr(1, title_x, title)
+            except curses.error:
+                pass
+            dialog.attroff(curses.A_BOLD)
 
-        dialog.refresh()
+            # Display visible lines
-        dialog.getch()
+            visible_lines = all_lines[scroll_offset:scroll_offset + dialog_h - 6]
+            for i, line in enumerate(visible_lines):
+                try:
+                    # Truncate line if too long for dialog width
+                    truncated_line = line[:dialog_w - 4]
+                    dialog.addstr(3 + i, 2, truncated_line)
+                except curses.error:
+                    pass
+
+            # Footer with scroll indicators
+            if max_scroll > 0:
+                footer = f"↑/↓ Scroll ({scroll_offset + 1}/{len(all_lines)})  Any other key to close"
+            else:
+                footer = "Press any key to close"
+            footer_x = max(2, (dialog_w - len(footer)) // 2)
+            try:
+                dialog.addstr(dialog_h - 2, footer_x, footer[:dialog_w - 4], curses.color_pair(3))
+            except curses.error:
+                pass
+
+            dialog.refresh()
+
+            # Handle input
+            key = dialog.getch()
+            if key == curses.KEY_UP and scroll_offset > 0:
+                scroll_offset -= 1
+            elif key == curses.KEY_DOWN and scroll_offset < max_scroll:
+                scroll_offset += 1
+            elif key == curses.KEY_PPAGE:  # Page Up
+                scroll_offset = max(0, scroll_offset - (dialog_h - 6))
+            elif key == curses.KEY_NPAGE:  # Page Down
+                scroll_offset = min(max_scroll, scroll_offset + (dialog_h - 6))
+            else:
+                # Any other key closes the dialog
+                break
 
     def _save_nav_position(self):
         """Save current navigation position before changing views"""