Per-tile stream quality (high/low), fps cap, latency flags

Cameras carry multiple stream URLs (streams: high/medium/low); each
tile picks one via Quality (auto/high/low). Small tiles can pull the
low substream to cut Pi decode load. discover --enable-rtsp takes a
comma list (high,low), enables each channel, records all enabled ones.
TUI: q cycles a tile quality (shown in the tile); discover enables
high+low. Player: --framedrop + low-delay demuxer flags; player.max_fps.

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

README.md

@@ -46,7 +46,18 @@ On the display device:
 Debian / Raspberry Pi OS: `sudo apt install sway mpv foot`
 Arch: `sudo pacman -S sway mpv foot`
 
-To build: Go 1.23+ (only on your dev machine; the Pi just needs the binary).
+To build: **Go 1.23+**. You can build on your dev machine and copy the binary,
+or build on the Pi itself.
+
+> ⚠️ Debian / Raspberry Pi OS ships **Go 1.19** via `apt`, which is too old
+> (`log/slog` needs 1.21+). Install a current Go into `~/.local/go` and put it
+> first on `PATH` — do **not** rely on the system `go`:
+> ```sh
+> curl -sSLO https://go.dev/dl/go1.23.4.linux-arm64.tar.gz     # match uname -m
+> rm -rf ~/.local/go && mkdir -p ~/.local && tar -C ~/.local -xzf go1.23.4.linux-arm64.tar.gz
+> echo 'export PATH=$HOME/.local/go/bin:$PATH' >> ~/.profile && export PATH=$HOME/.local/go/bin:$PATH
+> go version   # must show 1.23+, not 1.19
+> ```
 
 ## Build
 
@@ -55,6 +66,9 @@ make build     # native binary -> bin/rtsp-streamer
 make pi        # Raspberry Pi 4, 64-bit OS (arm64) -> bin/rtsp-streamer-arm64
 make pi32      # 32-bit Pi OS (armv7)              -> bin/rtsp-streamer-armv7
 make test
+make install   # build native + copy to /usr/local/bin (auto-sudo)
+make deploy    # install + restart the kiosk session
+rtsp-streamer version   # prints the baked-in git commit / build date
 ```
 
 ## Configure