fix: add navigationBarsPadding to composer / agent editor (bottom nav overlap)

[talwayh1]

Summary

Fixes the prompt composer (and the agent editor) being partially hidden behind the system navigation bar on devices with gesture navigation or 3-button navigation (e.g. Xiaomi MIUI/HyperOS, Samsung, Pixel with gesture mode).

Problem

MainActivity calls enableEdgeToEdge(), so the UI extends behind the system bars. The bottom-anchored input areas only applied imePadding():

Column(Modifier.imePadding()) { ... ComposeBar(...) }

imePadding() only consumes the IME (software keyboard) insets. When the keyboard is dismissed, the navigation bar insets are still present, and the composer sits behind the gesture bar / 3-button nav — the text field and send button are partially covered and hard to tap.

Fix

Chain navigationBarsPadding() after imePadding() on both bottom-anchored containers:

• SessionDetailScreen — the composer Column in the Scaffold bottomBar
• AgentDetailScreen — the root editor Column

Column(Modifier.imePadding().navigationBarsPadding()) { ... }

The ordering is safe in both states:

• Keyboard open: the IME consumes the navigation-bar area, so the navigation-bar insets are 0 and navigationBarsPadding() adds nothing extra.
• Keyboard closed: imePadding() is 0 and navigationBarsPadding() lifts the composer fully above the navigation bar.

Test plan

• Reproduced on a Xiaomi device (gesture nav): composer partially covered by the gesture bar before the fix
• After the fix in a local build: composer sits fully above the navigation bar; typing + send both work
• CI build passes (changes are 2 lines + 1 import, additive)

Related

Fixes the issue about the composer being covered by the virtual navigation bar.

[talwayh1]

Fixes #6