feat: nav to coming soon on send contacts and activity assign

[ovitrif]

Fixes #607
Closes #627

Description

1. Adds nav to the Coming Soon in-sheet page on tap of Send → Contact button
   • Introduces an implementation of the Coming Soon screen as a sheet page
2. Adds nav to the Coming Soon standalone sheet on tap of Activity Details → Assign button
   • Introduces a standalone Coming Soon sheet
3. Bumps version

versionCode = 168
versionName = "2.0.0-rc.2"

Preview

Send → Contact	Activity Details → Assign
Android.Studio.2026-01-16.002618.mp4	Android.Studio.2026-01-16.002627.mp4

QA Notes

Tests:

1. Send → Contact
   • Open the wallet screen
   • Tap Send to open the Send sheet
   • Tap the Contacts button
   • Test the Coming Soon sheet page that appears
2. Activity Detail → Assign
   • Tap on any Activity row either in one of the wallet screens (Home, Savings or Spending)
   • Tap the Assign button
   • Test the Coming Soon sheet that appears

[ovitrif]

drafted to implement the Coming Soon sheet for Assign button, to close:

• [Bug]: Activity: "Assign" button does nothing #627

[claude]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.

[jvsena42]

tACK