Move card-editor actions into a bottom app bar

[bootuz]

Summary

• Moves the card editor's three actions — Add image, Record audio, and Also create reverse card — out of inline chips and into a Material BottomAppBar.
• Promotes Save to the bar's primary-action FAB (removed from the top app bar). The FAB shows a muted/disabled() state until the card is valid.
• The bar floats above the keyboard (imePadding) and extends into the navigation-bar inset so there's no blank strip below it.
• Behavior parity preserved: image/audio icons hide once attached, uploading spinners, mic→stop while recording, reverse toggle on new cards only. Inline image-preview / audio-attached remove blocks are unchanged.
• Stable androidx.compose.material3 1.4.0 only — no dependency bump, no alpha/Expressive APIs.

Implementation notes

• CardFormScreen.kt: Scaffold(bottomBar = { BottomAppBar(actions = …, floatingActionButton = …) }); CardFormContent's parameter list is unchanged (purely presentational).
• AzriNavHost.kt: the cardForm route releases the bottom inset (top + sides only) so its own BottomAppBar can paint into the navigation-bar area; every other route keeps the existing inset handling (guarded by route, RTL-correct).
• CardFormContentTest.kt: chip-text assertions → onNodeWithContentDescription.

Test Plan

• ./gradlew :app:testDebugUnitTest — green
• ./gradlew :app:assembleDebug — debug APK builds
• ./gradlew :app:compileDebugAndroidTestKotlin — androidTest compiles
• Manual (Pixel 10 Pro emulator): bar shows the 3 actions + Save FAB; floats above the keyboard while typing; reaches the screen's bottom edge (no white strip) with the keyboard closed; Save muted until valid.

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