feat(android): native mDNS discovery, host naming, touch mouse, stock selects

Discovery: replace the flaky per-OEM NsdManager with the same mdns-sd browse
the Linux/Windows clients use, in the Rust core over JNI and polled by Kotlin
(discovery.rs + nativeDiscovery{Start,Poll,Stop}); Kotlin keeps only the Wi-Fi
MulticastLock + permission UX. IPv4-only (the core can't dial a bare/scoped v6
literal); daemon + fold-thread cleanup on every failure path; field
sanitization so a rogue advert can't corrupt the picker snapshot. Discovery
now starts regardless of NEARBY_WIFI_DEVICES (raw multicast only needs the
MulticastLock) — a denial no longer kills it forever. ParseTxtTest replaced by
ParseRecordTest.

Hosts: hide already-saved hosts from the "Discovered" section (match by
fingerprint, else address:port — mirrors the Apple client); add an optional
Name field to the Add-host sheet and a Rename action on saved cards.

Input: touch -> absolute mouse "direct pointing" like the Apple client — the
host cursor follows the finger (new nativeSendPointerAbs -> MouseMoveAbs). Tap
= left click, two-finger tap = right click, two-finger drag = scroll,
tap-then-drag = left-drag, three-finger tap = HUD toggle.

Settings: revert the dropdowns to the stock ExposedDropdownMenuBox look (a
controller-focus UI will come separately); even out the Add-host field gaps.

Docs updated (CLAUDE.md, client READMEs, docs-site status).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

clients/android/native/Cargo.toml

@@ -19,6 +19,12 @@ crate-type = ["cdylib"]
 punktfunk-core = { path = "../../../crates/punktfunk-core", features = ["quic"] }
 jni = "0.21"
 log = "0.4"
+# LAN host discovery: browse the host's `_punktfunk._udp` mDNS advert — the SAME crate + service the
+# Linux/Windows clients use (`clients/linux/src/discovery.rs`), replacing Android's per-OEM
+# `NsdManager` system daemon with one tested browse path. Pure Rust (socket2/if-addrs/mio), so it
+# cross-compiles to the Android targets AND builds on the host (the JNI seam links into
+# `cargo build --workspace`). Kotlin keeps only the Wi-Fi `MulticastLock` + permission UX.
+mdns-sd = "0.20"
 
 # Android-only deps. Gated so `cargo build --workspace` on the Linux/macOS dev boxes + CI still
 # compiles this crate (as a host cdylib) — the Android-framework glue (logging now; AMediaCodec via