Promote Xevious (U) and Zanac (U) from _wip/ to NROM/

- Xevious (U): Promoted from _wip/NROM/Xevious (U)/ to NROM/Xevious (U)/
  - Pass 3 complete: 34.5% code coverage, 143 semantic entry points,
    4 named data tables, ~20 semantic ZP aliases
  - NROM mapper 0, 32 KB PRG, 8 KB CHR, horizontal mirroring

- Zanac (U): Promoted from _wip/UNROM/Zanac (U)/ to NROM/Zanac (U)/
  - Pass 3 complete: 34.5% code coverage (bank 7 only), 133 semantic
    entry points, 26 named data tables, 14 semantic ZP aliases
  - UNROM mapper 2, 128 KB PRG (8 banks), no CHR
  - Bank 7 fixed at CPU -; banks 0-6 switchable at 000-
  - Bank 7 assembled separately as prg.07.s with .org

Both projects build byte-identical. Updated root README.md inventory,
per-project details, and WIP.md accordingly.

Move Zanac (U) to UNROM/ mapper directory

Zanac (U) is a UNROM (mapper 2) game, not NROM (mapper 0). Move it to
the correct mapper directory and update README.md and WIP.md references
accordingly. Update project counts in WIP.md (857->856 total, UNROM
98->97 projects).

Promote Mermaids of Atlantis (U) from _wip/ to MAPPER8/

Additional cleanup of Mermaids of Atlantis

MAPPER8/Mermaids of Atlantis (U)/label_map.tsv

@@ -0,0 +1,17 @@
+label	Label_801B	Sub_801B_Entry_801B
+label	Label_8036	Sub_8036_Entry_8036
+label	Label_8038	Sub_8036_OnNonnegative_8038
+label	Label_8057	Sub_8036_JoinBranchPaths_8057
+label	Label_8062	Sub_8036_OnNonzero_8062
+label	Label_806B	Sub_8036_OnCarrySet_806B
+label	Label_8083	Sub_8083_StoreAndContinue_8083
+label	Label_8189	Sub_8083_Entry_8189
+label	Label_FF2F	Sub_8764_OnCarryClear_FF2F
+label	Label_FF3E	Sub_FF3E_CallNext_FF3E
+label	Label_FF49	Sub_FF49_JumpNext_FF49
+label	Label_FF4C	Sub_FF4C_StoreAndContinue_FF4C
+label	Label_FF4E	Sub_FF4C_OnNonzero_FF4E
+label	Label_FF50	Sub_FF4C_OnNonzero_FF50
+label	Label_FF57	Sub_FF57_Return_FF57
+label	Label_FF60	Sub_FF57_OnNonzero_FF60
+label	Label_FF62	Sub_FF62_Return_FF62