[fix](trx-rs): install binaries under user home

Default installation and removal to /home/sjg/.local/bin while preserving explicit prefix and binary-directory overrides. Update the service examples and README to match.

Assisted-By: OpenAI Codex (GPT-5)
Signed-off-by: Stan Grams <sjg@haxx.space>

script/uninstall.sh

@@ -11,7 +11,7 @@ set -euo pipefail
 
 BINARIES=(trx-server trx-client trx-configurator)
 
-PREFIX="${PREFIX:-/usr/local}"
+PREFIX="${PREFIX:-$HOME/.local}"
 BINDIR="${BINDIR:-}"
 PURGE=0
 
@@ -23,7 +23,7 @@ usage() {
 Usage: script/uninstall.sh [options]
 
 Options:
-  --prefix DIR   Install prefix binaries were installed under (default: /usr/local)
+  --prefix DIR   Install prefix binaries were installed under (default: \$HOME/.local)
   --bindir DIR   Directory binaries were installed to (overrides --prefix)
   --purge        Also delete the user config directory ($CONFIG_DIR)
   -h, --help     Show this help