fix(parse): fn stays an ordinary name unless a function name follows on the same line

`fn name` read `while p < fn and ...` as a reference to a function called `and`, which broke
tools/ludic-cli/glgen.ludic and so the dev tool's own build. A reference now needs the name on
the same line and not one of and / or / not / in / is. The threads example checks `fn` as a
local before `and`. Reseeded; bootstrap-cfree reproduces the seed.

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

examples/library/threads.ludic

@@ -49,6 +49,7 @@ program Threads {
     if (Sync.cpu_count() > 1 and pooled > 0) or (Sync.cpu_count() == 1 and pooled == 0) { print(6) }
 
     Job.parallel_for(0, fn square, sq)       # nothing to do: returns at once
-    print(7)
+    let fn = 7                                # `fn` is still an ordinary name, before `and` too
+    if 0 < fn and fn < 8 { print(fn) }
   }
 }