Portable Ithaca capture node: one install for every Jetson

Extract the install that was applied by hand to the Jetson Nano into a single
checkout that builds itself for whatever Jetson it lands on.

The two nodes on the rig share no JetPack — tegra210 caps at 4, tegra234 needs
5+ — so nothing binary is portable between them. The source and the procedure
are: install.sh detects the platform (L4T / JetPack / SoC), installs deps,
builds the OrbbecSDK and the preview server from source locally, and generates
a per-user config and systemd unit. The tested bridge.py ships verbatim; all
machine-specific paths live in the generated config, so it stays unmodified —
its one hardcoded path is made home-relative.

The retired GStreamer/RTSP target is dropped: the direct route encodes no video.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

scripts/build_server.sh

@@ -0,0 +1,29 @@
+#!/usr/bin/env bash
+# Builds ithaca_rgbd_server against the SDK build_sdk.sh located. Prints nothing
+# but the binary path on success.
+set -euo pipefail
+
+here=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+repo=$(cd "$here/.." && pwd)
+
+# SDK locations come from build_sdk.sh (or the environment, when a caller already
+# knows them).
+if [[ -z "${OB_SDK_ROOT:-}" || -z "${OB_SDK_BUILD:-}" ]]; then
+    eval "$("$here/build_sdk.sh")"
+fi
+
+build="$repo/server/build"
+mkdir -p "$build"
+(
+    cd "$build"
+    cmake "$repo/server" \
+        -DCMAKE_BUILD_TYPE=Release \
+        -DOB_SDK_ROOT="$OB_SDK_ROOT" \
+        -DOB_SDK_BUILD="$OB_SDK_BUILD" \
+        -DOB_SDK_GENERATED="${OB_SDK_GENERATED:-$OB_SDK_ROOT/build/src/generated}" >&2
+    make -j"$(nproc)" >&2
+)
+
+bin="$build/ithaca_rgbd_server"
+[[ -x "$bin" ]] || { echo "build failed: $bin absent" >&2; exit 1; }
+echo "$bin"