feat: Adding Emoji Picker, Clipboard History, and Text Indentation.

### Is your feature request related to a problem? Please describe.

Yes. The current state of Keyman on mobile platforms lacks core usability features expected of a modern keyboard in the year 2025. Its current build hinders fluid writing, multitasking, cross-app use, and fast content handling—placing it behind other modern keyboards in daily usefulness and workflow support.

### Describe the solution you'd like

Integrate the following utility-bound features into Keyman for Android, iOS, and iPadOS:

- Emoji Picker: Access to native emoji sets/styles from Android or iOS/iPadOS, with a seamless in-keyboard picker that matches the OS style and emoji updates. No standalone popup—fully native feel.
- Clipboard History: Built-in clipboard with a rotating stack of up to 10 entries. Entries expire after 12 hours unless pinned. Must support pinning and manual clearing.
- Text Indentation Tools: On-screen arrow keys for moving the cursor (←↑↓→), a shift-based selection system, and buttons for Cut, Copy, and Paste. This is needed for devices lacking full hardware navigation tools.
- Keyboard Split: On tablets and horizontal phones, enable split-layout to allow thumb-typing. This improves ergonomics and matches layouts already standard on many rival keyboards.
- Translation Hook (Optional): Allow user to add their own API key (LibreTranslate, DeepL, OpenL) for in-keyboard translation of selected text. Must be toggleable, not automatic. Could be nested in a utility row.

### Describe alternatives you've considered

- External clipboard managers (not reliable and don’t integrate well).
- Third-party emoji apps (slow and break typing flow).
- External translation apps or browser tabs (slow, out-of-context).
- Switching keyboards mid-task to use text navigation tools (annoying and error-prone).
- Other keyboards like Gboard or SwiftKey, but they do not support full custom layouts like Keyman.

### Related issues

- Usability gap between Keyman and major keyboards.
- Typing fatigue on large-screen devices.
- Slowed typing due to lack of quick cursor and clipboard handling.
- Emoji usage hampered due to layout/style mismatch.
- No built-in translation support leads to switching away from keyboard and losing flow.

### Keyman apps

- [x] Keyman for Android
- [x] Keyman for iPhone and iPad
- [ ] Keyman for Linux
- [ ] Keyman for macOS
- [ ] Keyman for Windows
- [ ] Keyman Developer
- [ ] KeymanWeb
- [ ] Other - give details at bottom of form

### Keyman version

18.0.235

### Operating system

Android, iOS

### Device

_No response_

### Target application

Keyman for Android, Keyman for iPhone/iPad

### Browser

_No response_

### Keyboard name

_No response_

### Keyboard version

_No response_

### Language name

_No response_

### Additional context

_No response_