Hardware docs: board photos, schematic scan, GAL fuse dump

Organize the restoration source material under docs/hardware/:
- 9 board photos (renamed from Signal timestamps, index in README)
- Scans_018-014.pdf: 7-sheet VWE schematic set (RIO_1407 CPU/power/IO,
  PBE_1401 buttons, KEY_1402 keypad, DSP_1408 display, AMP_PLT 1413 amp)
- GAL20v8a_5764.JED: fuse map of the 1407's U7 memory decoder

README documents the board family, the 68HC11 memory map decode path,
the pod-bus signal set and jumper addressing, and cross-links PROTOCOL.md
and rio-firmware/.

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

docs/hardware/gal/GAL20v8a_5764.JED

@@ -0,0 +1,38 @@
+
+
+Device    :    GAL20V8A
+
+Created By:    http://www.autoelectric.cn
+
+Date      :    2023-03-09 19:02
+
+*QP24
+
+*QF2706
+
+*G0
+
+*F0
+
+*L00000 11111111111111111111111111111111
+
+*L00032 11111111111111011111111111111111
+
+*L00064 11111111110111110000000000000000
+
+*L00320 11111111111111111111111111111111
+
+*L00352 11111111111111111111111111111111
+
+*L00384 11111110111111110000000000000000
+
+*L00640 11111111111111111111111111111111
+
+*L00672 11111111100101111011101110111011
+
+*L00704 10111011101101110000000000000000
+
+*L00960 11111111111111111111111111111111
+
+*L00992 11111111111001111111111111111111
+