Test the wands, staffs and bolt geometry of sticks.c (closes #6)

game/sticks.go was the largest under-tested file in the repo: 534 lines,
23 functions and a single test. It now has two test files, both written
against the C reference (git show origin/c-master:sticks.c) rather than
against the current Go code, so they can catch divergence instead of
recording it.

game/sticks_test.go covers every zap handler that had none — light in a
room and in a corridor, drain-life's too-weak refusal (which returns
before o_charges--), drain's hit-point split and its kill arm,
drainReaches for all three of C's clauses, invisibility and the flytrap
release, polymorph's detach/re-attach dance with the pack, under-
character and delta-clobbering it does on the way, cancellation, both
teleport wands, magic missile, haste/slow in both directions, fix_stick's
damage and charge formulas, and charge_str.

game/bolt_test.go covers fire_bolt: dirch for all eight directions,
boltBounces including the door the hero stands on, an end-to-end flight
asserting the path and resting square, bounces off both wall
orientations, off a corner and diagonally off a wall (which pins C's rule
that a bounce negates both components rather than reflecting), a bounced
bolt striking the hero who fired it, the strike and miss arms, and the
dragon that shrugs off a flame but not a lightning bolt.

The tests read the flight path off the screen: fire_bolt paints its trail
and then paints chat() back over every square it recorded, so on an
otherwise blank screen the non-blank cells are exactly the squares the
bolt occupied, and the walls it bounced off are absent because C undoes
the record before the mvaddch. Determinism comes from a pinRng helper
that searches for a seed whose next draw is the wanted value, and from a
level the tests carve themselves with the generator's own drawRoom. The
hero is fortified wherever a bolt can reach him, since death exits the
process.

No divergence from C was found. Two notes are recorded in the test
comments: fire_bolt's "ch != 'M'" guard is a tautology, because winat is
t_disguise whenever a monster stands there, and the door-under-hero
exception can only be tested by the fact that the run terminates.

TODO.md

@@ -67,7 +67,7 @@ wizard commands).
   `Rng`, never predicting it) and from a level the tests carve themselves
   through `drawRoom`, since bounce geometry and `drain`'s room/passage/door
   reach only mean something against known walls and a known passage number. All
-  21 mutations tried against the new tests were caught.
+  27 mutations tried against the new tests were caught.
 
 - 2026-08-09 Command dispatch audit (`audit/command-switch-coverage`, closes
   #31): checked every case label in C's `command.c` against this port's