ww: lib tests run via -T test mode; bare mains retired (closes @test conversion)

'ww test' gains the istest build path (-T injection in build_one/
buildone) and do_test/dotest accept -I, mirroring do_run - both twins.
The 35 converted lib tests drop their interim bare mains (-T
synthesizes the entry from @test fns and rejects a user main); their
35 C run-drivers flip 'ww run' -> 'ww test'; 989_lib_byteid compiles
lib tests under -T (8 user-main probe fixtures stay non-T, gated on
the fixture field). Abort-on-first-failure stands until the deferred
record-and-continue harness lands with the multi-package arc.

lib/time/timetest.ww

@@ -157,22 +157,3 @@ import time;
 	assert(!(time.compare(a, b) != -1i8));
 	assert(!(time.compare(b, a) !=  1i8));
 };
-
-export fn main() i32 = {
-	constants();
-	nowmonotonic();
-	nowrealtime();
-	addzero();
-	addpos_nocarry();
-	addpos_carry();
-	addpos_fullsecond();
-	addneg_noborrow();
-	addneg_borrow();
-	diffsimple();
-	diffneg();
-	comparelt();
-	comparegt();
-	compareeq();
-	comparensec_only();
-	return 0;
-};