fix: Prevent Enter key propagation from filter modal to main view

Fixed event propagation issue where pressing Enter in the filter modal
would both apply filters AND trigger drill-down action in the main view.

**Issue**: After pressing Enter to apply filters, app would immediately
drill down into the first row of the table.

**Root Cause**: Enter key event was not stopped, so it bubbled up from
the modal to the main app's on_data_table_row_selected handler.

**Fix**: Added event.stop() calls to ALL keyboard shortcuts in FilterScreen:
- Enter/Space: Stop before applying filters
- Escape: Stop before dismissing
- h: Stop before toggling hidden checkbox
- t: Stop before toggling transfers checkbox

**This is a common Textual pattern**: Modal screens must stop key events
to prevent them from reaching parent widgets.

**Affected Workflow:**
1. User presses 'f' to open filters
2. User presses 'h' or 't' to toggle options
3. User presses Enter to apply
4. Before: Would drill down immediately
5. After: Cleanly dismisses modal, no drill-down

All 465 tests passing, pyright clean.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: wesm

moneyflow/screens/credential_screens.py

@@ -591,17 +591,21 @@ async def on_button_pressed(self, event: Button.Pressed) -> None:
     def on_key(self, event: Key) -> None:
         """Handle keyboard shortcuts for filter modal."""
         if event.key == "escape":
+            event.stop()  # Prevent propagation
             self.dismiss(None)
         elif event.key in ("enter", "space"):
+            event.stop()  # Prevent propagation to parent
             # Apply filters
             show_hidden = self.query_one("#show-hidden-checkbox", Checkbox).value
             show_transfers = self.query_one("#show-transfers-checkbox", Checkbox).value
             self.dismiss({"show_hidden": show_hidden, "show_transfers": show_transfers})
         elif event.key == "h":
+            event.stop()  # Prevent propagation
             # Toggle hidden checkbox
             checkbox = self.query_one("#show-hidden-checkbox", Checkbox)
             checkbox.value = not checkbox.value
         elif event.key == "t":
+            event.stop()  # Prevent propagation
             # Toggle transfers checkbox
             checkbox = self.query_one("#show-transfers-checkbox", Checkbox)
             checkbox.value = not checkbox.value