android: the falcon on the launcher — a real adaptive icon, with the monochrome layer

The phone has been wearing tauri's logo. `tauri android init` writes the
generated project's `res/` from its own template and never reads
`src-tauri/icons/android/`, which has carried the falcon since 50afa6a, and the
detour build runs cargo and Gradle directly — so nothing ever copied it across:
the two dominant colours in the packaged `mipmap-xxxhdpi/ic_launcher.png` are
`#24c8db` and `#ffc131`, tauri's own brand cyan and amber. `src-tauri/android/res/`
is the app module's res now, tracked, and `build.sh` and `dev.sh` copy the whole
tree into `gen/android` before Gradle, because that project is regenerated and
gitignored and an asset that only lives there is an asset that disappears.

It is a real adaptive icon: the kit's foreground and its **monochrome** layer at
five densities, the legacy mipmaps under it, and the background as one
`#FF05080B` colour resource rather than five identical flat PNGs, so the gradient
being mocked separately replaces one file. The kit's own XML could not ship — it
points every layer at `@drawable/` while shipping them as PNGs under `mipmap-*`,
and in the generated project two of those three references resolve to Android
Studio's template robot rather than failing — so the overlay's XML says
`@mipmap/` and `@color/`, and its colour file takes the same name tauri's does,
because two files declaring one colour is a hard aapt2 error.

Losing the copy would be silent — the APK still builds, still installs, and wears
the old logo with nothing in the log — so `verify-icon.sh` opens every APK both
scripts make and reads the resources back out: the two `mipmap-anydpi-v26` XMLs
present, and four PNG names at five densities byte for byte from the overlay. A
release APK keeps neither the bytes nor the names — AGP re-encodes every PNG and
shortens every resource path — so that path asks `aapt2 dump resources` what each
name points at and compares pixel dimensions instead; 72×72 at hdpi still tells
the kit's icon from tauri's 49×49. No walk step: a launcher icon is not reachable
from inside the app, and the masking and the themed layer want a minute with the
phone's home screen.