fix: Final branding cleanup - quit dialog and widgets

Fixed remaining user-visible 'Monarch' references:

- screens/credential_screens.py: 'Quit Monarch TUI?' → 'Quit moneyflow?'
- screens/review_screen.py: 'Commit to Monarch (C)' → 'Commit Changes (C)'
- widgets/__init__.py: 'Monarch TUI' → 'moneyflow TUI' in docstring

All user-facing text now uses 'moneyflow' branding consistently.

Remaining 'Monarch' references are appropriate:
- MonarchTUI class name (internal implementation detail)
- backends/monarch.py (Monarch backend implementation)
- monarchmoney.py (external GraphQL client)
- Comments mentioning Monarch as a supported platform

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

@@ -465,7 +465,7 @@ def __init__(self, has_unsaved_changes: bool = False):
 
     def compose(self) -> ComposeResult:
         with Container(id="quit-dialog"):
-            yield Label("⚠️  Quit Monarch TUI?", id="quit-title")
+            yield Label("⚠️  Quit moneyflow?", id="quit-title")
 
             if self.has_unsaved_changes:
                 yield Static(

moneyflow/screens/review_screen.py

@@ -86,7 +86,7 @@ def compose(self) -> ComposeResult:
             with Container(id="review-footer"):
                 yield Static("c=Commit | Esc=Cancel", classes="footer-instructions")
                 with Container(id="button-container"):
-                    yield Button("Commit to Monarch (C)", variant="primary", id="commit-button")
+                    yield Button("Commit Changes (C)", variant="primary", id="commit-button")
                     yield Button("Cancel (Esc)", variant="default", id="cancel-button")
 
     async def on_mount(self) -> None:

moneyflow/widgets/__init__.py

@@ -1,4 +1,4 @@
-"""Custom Textual widgets for Monarch TUI."""
+"""Custom Textual widgets for moneyflow TUI."""
 
 from .help_screen import HelpScreen