Put the compaction window's reasoning on the compaction window

4a40578 inserted AUTOCOMPACT_WINDOW between an existing doc comment and
the constants it described, so rustdoc attached "the session directory's
copies of the process's standard streams" to the compaction window and
left STDIN_FIFO, STDOUT_LOG and STDERR_LOG undocumented. Moving the new
constant below them restores both.

Verified: 68 tests, clippy clean, rustfmt clean.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

server/src/session/claude.rs

@@ -172,6 +172,10 @@ impl Queue {
 /// the attach path must agree about which file is which; if they drift,
 /// a reattached session reads a file nothing is writing and simply looks
 /// idle forever.
+const STDIN_FIFO: &str = "stdin.fifo";
+const STDOUT_LOG: &str = "stdout.log";
+const STDERR_LOG: &str = "stderr.log";
+
 /// The context size the CLI compacts at, rather than letting it choose.
 ///
 /// Left to `auto` a phone session drifts: these run for hours, nobody
@@ -191,10 +195,6 @@ impl Queue {
 /// value. Raise it if sessions start losing the thread.
 const AUTOCOMPACT_WINDOW: &str = "100k";
 
-const STDIN_FIFO: &str = "stdin.fifo";
-const STDOUT_LOG: &str = "stdout.log";
-const STDERR_LOG: &str = "stderr.log";
-
 /// How often a reader with nothing to read looks again.
 ///
 /// A poll rather than a watch: the alternative is an inotify dependency