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>

CLAUDE.md

@@ -199,7 +199,9 @@ Low-latency desktop/game streaming stack, Linux-first, with a shared Rust protoc
    `punktfunk-core`; phone + Android TV): NDK `AMediaCodec` hardware HEVC decode → `SurfaceView` incl.
    **HDR10** (Main10/BT.2020 PQ) with low-latency tuning + a live stats HUD (`decode.rs`/`stats.rs`),
    Opus/Oboe audio + mic uplink (`audio.rs`/`mic.rs`), gamepad input with rumble/HID feedback
-   (`feedback.rs`), `NsdManager` mDNS discovery, SPAKE2 PIN pairing + TOFU (Keystore identity +
+   (`feedback.rs`), **native `mdns-sd` mDNS discovery** (`discovery.rs`, polled over JNI — the same
+   browse the Linux/Windows clients use, replacing the flaky per-OEM `NsdManager`; Kotlin keeps only
+   the `MulticastLock` + permission UX), SPAKE2 PIN pairing + TOFU (Keystore identity +
    known-host store), Compose UI (Connect/Settings/Stream) with D-pad/controller focus nav. Built for
    `arm64-v8a` + `x86_64`; published to Google Play (Internal Testing) via `android.yml`
    (`ci/play-upload.py`). Next: real-device gamepad/HDR live-verify, presenter/latency polish.