Plexamp Lite 1.14.1: read-ahead no longer cut off ("Unexpected end of stream")

Two causes, both fixed:
- Plex keeps one file stream per device and cuts the one in progress when another starts, so the read-ahead
  and the player cut each other off. Whole-file fetches (read-ahead, downloads, download-first) now ask for
  the file as a download (?download=1), which Plex leaves out of that rule; the plain address follows for
  servers that refuse downloads.
- Http.abort closed the socket of a response already read to the end, whose connection was back in the pool
  and could be carrying the read-ahead. abort now leaves finished responses alone (test/PoolAbortTest.java).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

test/run_pool_abort.sh

@@ -0,0 +1,10 @@
+#!/bin/bash
+# Runs test/PoolAbortTest.java on this computer (JDK 11+; Bouncy Castle from the toolchain, Android's Log stubbed).
+set -euo pipefail
+cd "$(dirname "$0")/.."
+T=${TOOLS:-$HOME/android-toolchain}
+J=${JAVA_HOME:-/opt/homebrew/opt/openjdk@17}/bin
+out=$(mktemp -d)
+trap 'rm -rf "$out"' EXIT
+"$J/javac" -nowarn -d "$out" -sourcepath "src:$T/bcsrc:test/stub" test/PoolAbortTest.java 2>&1 | grep -v '^Note:' || true
+"$J/java" -cp "$out" PoolAbortTest