### Problem
●In edgeless mode, when starting to edit, `note-block` exhibits two
types of invalid caret behavior:
(1)**Title Region Misalignment**: Clicking on the title region
incorrectly generates the caret in the first line of the note content,
rather than in the title itself.
(2)**Vanishing Caret at Line End**: When clicking in the empty space
beyond the end of a text section, the caret appears momentarily at the
line's end but disappears immediately.
●The following video demonstrates these issues:
https://github.com/user-attachments/assets/db9c2c50-709f-4d32-912c-0f01841d2024
### Solution
●**Title Click Interception**: Added a check to determine if the click
coordinates fall in the title region. If so, the caret positioning is
now handled by a dedicated logic path. Otherwise, it falls back to the
existing note-content logic as before.
●**Range Normalization**: When the generated `range.startContainer` is
not a `TextNode`, try to find a most appropriate `TextNode` and update
the `range` accordingly.
### After
●The video below shows the behavior after this fix.
https://github.com/user-attachments/assets/b2f70b64-1fc6-4049-8379-8bcf3a488a05
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **Bug Fixes**
* Clicking a page block title no longer creates unwanted paragraphs and
reliably focuses the title.
* Paragraph creation now occurs only when needed and focus is applied
only after successful creation.
* Click coordinates are clamped to container bounds to prevent misplaced
cursors or focus.
* **Improvements**
* Caret normalization: clicks place the caret at the last meaningful
text position for consistent single-cursor behavior.
* **Tests**
* Added end-to-end coverage for caret placement and focus transitions.
* New ratio-based click/double-click test utilities and a helper for
double-clicking note bodies.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
Close [BS-3404](https://linear.app/affine-design/issue/BS-3404/通过embed-doc时，插入的doc还是card-view，应该要默认embed-view)
<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit
- **New Features**
- Added the ability to insert and display embedded synced documents, supporting different link types based on editor mode and user preferences.
- Introduced new UI interactions and view options for embedded synced documents in edgeless mode.
- **Bug Fixes**
- Updated UI selectors and preference keys to ensure consistent behavior and correct application of user settings.
- **Tests**
- Added and updated end-to-end tests for embedding synced documents, including header interactions and viewport fitting.
- Improved test coverage for quick search insertion and edgeless embed synced doc features.
- **Chores**
- Renamed settings and updated exports to align with new embedding functionality.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
congzhou09