Promote CIRCUS from _wip to top-level project

Moves CIRCUS from _wip/CIRCUS to CIRCUS/ 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

Updates root OVERVIEW.md:
- Removes CIRCUS from _wip skeleton table (25 -> 23 skeletons)
- Adds CIRCUS as #12 in numbered inventory (BYTE-IDENTICAL, Pass 2/3)
- Updates summary count from 11 to 12 projects

CIRCUS/copilot/Makefile

@@ -0,0 +1,25 @@
+CA65 ?= ca65
+LD65 ?= ld65
+
+all: reconstructed.nes verify
+
+prg.o: prg.s symbols.inc locals.inc
+	$(CA65) -g -o $@ $<
+
+header.o: header.s
+	$(CA65) -g -o $@ $<
+
+chr.o: chr.s
+	$(CA65) -g -o $@ $<
+
+reconstructed.nes: header.o prg.o chr.o linker.cfg
+	$(LD65) -C linker.cfg -m reconstructed.map -Ln reconstructed.lbl -o $@ header.o prg.o chr.o
+
+verify: reconstructed.nes
+	cmp reconstructed.nes rom.nes
+	@echo "Byte-identical ROM verified."
+
+clean:
+	rm -f *.o reconstructed.nes reconstructed.map reconstructed.lbl
+
+.PHONY: all verify clean