fix: apply Y-axis flip in WireDragger.pin_world_xy

Library symbol pins are stored Y-up (positive Y is upward in the symbol
editor's coordinate system) but `.kicad_sch` is Y-down (positive Y is
downward in the schematic). `pin_world_xy` was returning `sym_y + ry`
without negating the rotated lib Y, so for any non-symmetric symbol
pin 1 and pin 2 ended up at swapped world positions.

For symmetric two-pin passives (R, C non-polarized) this was invisible
because pin 1 and pin 2 are electrically equivalent. For polarized
parts — electrolytic and polymer caps, diodes, MOSFETs, BJTs — it
silently swapped polarity. A label snapped to a polarized cap's pin 1
ended up on pin 2, which is catastrophic at first power-up.

The order matches eeschema's actual transformation:
  mirror in lib space → Y-flip to screen → rotate → translate.

The existing regression test in test_pin_locator_y_flip.py was already
written with the correct expected coordinates but the matching code fix
was never landed; that test now passes.

Three tests in test_move_with_wire_preservation.py had baked the buggy
expected coordinates into their assertions; updated those to the correct
y-flipped values. The touching-pin fixture had to flip R2's Y from
-7.62 to +7.62 so the two pins still meet under the corrected formula.

Verified end-to-end on a 46-component aerospace PDB schematic: all
8 polarized-part pins (4 polymer caps + 4 TVS diodes) now produce
world coordinates that match the labels actually placed in the file.

python/commands/wire_dragger.py

@@ -152,15 +152,16 @@ class WireDragger:
         """
         Compute the world coordinate of a pin given the symbol transform.
 
-        KiCAD applies mirror first (in local space), then rotation, then translation.
-        mirror_x negates the local X axis; mirror_y negates the local Y axis.
+        Library pins are stored Y-up; the schematic is Y-down. Order matches
+        eeschema: mirror in lib space → Y-flip to screen → rotate → translate.
+        Without the Y-flip, polarized parts get pin 1/pin 2 silently swapped.
         """
         lx, ly = px, py
         if mirror_x:
             lx = -lx
         if mirror_y:
             ly = -ly
-        rx, ry = _rotate(lx, ly, rotation)
+        rx, ry = _rotate(lx, -ly, rotation)
         return sym_x + rx, sym_y + ry
 
     @staticmethod
@@ -260,8 +261,7 @@ class WireDragger:
 
         # Remove existing (mirror ...) token(s)
         to_remove = [
-            i for i, sub in enumerate(item)
-            if isinstance(sub, list) and sub and sub[0] == mirror_k
+            i for i, sub in enumerate(item) if isinstance(sub, list) and sub and sub[0] == mirror_k
         ]
         for i in reversed(to_remove):
             del item[i]