Improved Probhat Layout

[RHJihan]

Discussed in #1368
Previous conversation on Probhat layout: #489

I have revised the Probhat layout based on an analysis of the original Probhat layout for PC, as well as its implementations in Ridmik Keyboard and Indic Keyboard.

Normal State	Shift State

Here are the key justifications for these changes:

1. Relocating the ো key:

• Moved to the second row, similar to Indic Keyboard and the current Probhat layout in HeliBoard.
• This reduces key density in the first row, making the layout more balanced.

2. Bengali period । placed in the standard position:

• Moved to replace the Latin period, aligning with the original Probhat layout and Ridmik Keyboard.

3. Dedicated key for ঞ and Placement of ঞ and ৃ :

• In the original Probhat layout, ঞ is on the number row in the Shift state. On mobile, it is currently buried in long-press options, making it harder to access.
• ঞ is frequently used in ligatures such as বিজ্ঞান, গঞ্জ, অঞ্জলি, জ্ঞান, etc. So ঞ requires a dedicated key than a long-press option.
• A dedicated key improves accessibility.
• On mobile, the comma key is positioned differently from a computer keyboard, freeing up space on the ৃ key.
• I placed ঞ in this available position.
• I am considering whether ঞ should be in the normal state and ৃ in Shift, or vice versa. I lean towards placing ঞ in the normal state and ৃ in Shift, as ঞ is more frequently used and this respects the original position of the ৃ key in Probhat.

4. Removal of the dedicated ॥ and ৳ key:

• ॥ is already accessible via long-press on the Bengali period key.
• Since ॥ is rarely used in Bengali, a dedicated key is unnecessary.
• ৳ is already accessible via Symbols Layout.