feat(parity): rsync 3.4.1 checksum/timeout/temp-dir/connectivity parity (#289 #295 #296)

#289 checksum/compression:
- -c/--checksum now implies the incremental content quick-check (without
  implying -t), so an unchanged file is skipped like rsync.
- --checksum-choice/--cc accepts xxh64/xxhash, xxh3, xxh128, md5 and auto;
  md4/sha1/none and the two-name form are rejected by name.
- --compress-choice/--zc rejects lz4/zlib/zlibx by name (zstd/none/auto kept).
- --checksum-seed=0 is randomized per transfer and sent on the wire.
- --skip-compress uses rsync 3.4.1's default suffix list; slash separators and
  dot-less suffixes are accepted.
- add --no-whole-file.

#295 timeouts/alloc/temp-dir:
- --timeout default 0 (disabled), --contimeout default 60; 0 disables both,
  plus --no-timeout/--no-contimeout.
- --max-alloc=0 means no allocation limit (was rejected).
- --temp-dir accepts any dir, requires it to exist, and falls back to a
  non-atomic copy on EXDEV instead of aborting.

#296 connectivity/daemon:
- -M/--remote-option is rejected for daemon/TCP destinations (SSH-only).
- --trust-sender clarified as receiver-local; server-path tests added.
- --stop-at accepts rsync's full date form (y-m-dTh:m etc.).

Adds unit and integration coverage; no wire-field change, PROTOCOL_VERSION stays
2.22.0.

tests/test_transport_tcp.c

@@ -144,14 +144,18 @@ static void test_client_delete_null() {
   client_delete(c);
 }
 
-/* Test tcp_set_timeouts with valid values */
+/* Test tcp_set_timeouts: a non-positive value disables the timeout (rsync's
+ * --timeout=0 / --contimeout=0), it is not a "leave unchanged" sentinel. */
 static void test_tcp_set_timeouts() {
-  /* Just verify the function doesn't crash with edge cases */
-  tcp_set_timeouts(0, 0);   /* zero means "don't change" */
-  tcp_set_timeouts(60, 20); /* normal values */
-  tcp_set_timeouts(-1, -1); /* negative means "don't change" */
-  /* If we got here without crashing, the test passes */
-  EXPECT_TRUE(true);
+  tcp_set_timeouts(0, 0);
+  EXPECT_EQ_INT(tcp_get_timeout_sec(), 0);
+  EXPECT_EQ_INT(tcp_get_contimeout_sec(), 0);
+  tcp_set_timeouts(60, 20);
+  EXPECT_EQ_INT(tcp_get_timeout_sec(), 60);
+  EXPECT_EQ_INT(tcp_get_contimeout_sec(), 20);
+  tcp_set_timeouts(-1, -1);
+  EXPECT_EQ_INT(tcp_get_timeout_sec(), 0);
+  EXPECT_EQ_INT(tcp_get_contimeout_sec(), 0);
 }
 
 /* Test client_connect with an invalid host (should fail gracefully) */