release: parallel command links, nine-level list nesting

Two development changes since the last snapshot.

perf(build): com/Makefile's recursive $(MAKE) commands inherited no
jobserver, so kdiag, kdesc and ktext linked one after another even though
they are independent links against the already-built library.  A clean
rebuild drops from 27.9 s to 23.1 s on an i9-14900KF and from 16.4 s to
13.8 s on an M5 Pro.

fix(list): LaTeX's built-in enumerate and itemize stop at four levels, so
a deeper @ol or @ul failed with "Too deeply nested".  sks/list/sty/list.sty
now redefines both through enumitem to allow nine, with explicit per-level
itemize markers, since \renewlist discards the built-in ones.

(from dev 15b822f06ee0)

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

com/Makefile

@@ -37,9 +37,12 @@ DEPFLAGS = -MMD -MP -MF $(@F).d
 
 .PHONY: all clean redo clang mac sks install
 
-# Default target: build dependencies first, then commands
+# Default target: build dependencies first, then commands. The commands are
+# three independent links against the finished library, so they run in
+# parallel (as mac/ and the sks/ components already do) rather than one after
+# another -- the serial links were about a quarter of a clean rebuild.
 all : | mac sks
-	$(MAKE) commands
+	$(MAKE) -j commands
 
 # Separate target to build commands (called after dependencies are ready)
 .PHONY: commands