Promote NES PowerPad Test Card (U) from _wip to top-level project

Moves NES PowerPad Test Card (U) from _wip/ to NES PowerPad Test Card (U)/ with full ROM build:
- Adds header.s, chr.s, linker.cfg (HEADER+PRG+CHR segments)
- Updates Makefile to build and verify reconstructed.nes vs rom.nes
- Adds rom.nes copy + copilot/rom.nes symlink per repo convention
- Verified byte-identical build

Pass 1 complete: full code/data classification (~7.2% code / ~92.8% data)
Pass 2 complete: routine headers for all ~50 labels, semantic naming for key
routines (Reset, NmiHandler, VramWrite, ReadPad, ProcessPads, etc.),
zero-page aliases in locals.inc (Zp00-Zp15)
Pass 3 complete: data tables named (PaletteData at ,
PadBitTableLives at )

Root OVERVIEW.md updated:
- Removes NES PowerPad Test Card from _wip skeleton table (21 → 20 skeletons)
- Adds NES PowerPad Test Card as #15 in numbered inventory (BYTE-IDENTICAL, Pass 2/3)
- Updates summary count from 14 to 15 projects

NES PowerPad Test Card (U)/copilot/locals.inc

@@ -0,0 +1,24 @@
+; NES PowerPad Test Card (U) zero-page aliases - Pass 2
+; Semantic names for addresses with observed usage patterns.
+
+Zp00               = $00 ; PPUCTRL shadow register
+Zp01               = $01 ; PPUMASK shadow register
+Zp02               = $02 ; VBlank flag (set by NMI, cleared by WaitForVBlank)
+Zp03               = $03 ; Frame counter / NMI tick counter
+Zp05               = $05 ; Score/digit temp
+Zp06               = $06 ; Pad 1 state byte 1 (shifted pad data)
+Zp07               = $07 ; Pad 1 state byte 2
+Zp08               = $08 ; Pad 1 state byte 3
+Zp09               = $09 ; Pad 1 state byte 4
+Zp0A               = $0A ; Pad 2 state byte 1
+Zp0B               = $0B ; Pad 2 state byte 2
+Zp0C               = $0C ; Pad temp / swap variable
+Zp0D               = $0D ; Pad mode / draw flag
+Zp0E               = $0E ; Shift counter / temp
+Zp0F               = $0F ; Delay counter
+Zp10               = $10 ; VRAM pointer low byte (indirect)
+Zp11               = $11 ; VRAM pointer high byte (indirect)
+Zp12               = $12 ; Score digit 1 accumulator
+Zp13               = $13 ; Score digit 2 accumulator
+Zp14               = $14 ; Score digit 3 accumulator
+Zp15               = $15 ; Score digit 4 accumulator