M-13: 21-level sweep matrix + D123 (C1 fix) + D124 (C2 Jungle fix)

WS4 level sweep driven to completion: 12/21 solo levels PASS
(load + render + no-crash). Full matrix in docs/LEVEL-STATUS.md,
reusable runner tools_pc/level_sweep.sh, WS6 checklist docs/LEVEL-PLAYTEST.md.

Fixes:
- D123 (tools_pc/d88_propdefs.py): crash class C1 on 6 levels
  (Dam/Runway/Frigate/Statue/Streets/Cradle). D122 fallout - the widened
  Vehichle/AircraftRecord.ailist slot was zeroed instead of carrying its
  read-before-write integer AI-list id, so prop.c -> ailistFindById(0) ->
  GAILIST_AIM_AT_BOND -> ai() ran a CHR aim list with a NULL chr ->
  chrIsNotDeadOrShot(NULL). New OBJ_ID_WORDS arm. 4 levels -> PASS,
  Runway falls through to C2. BUNKER1/Silo unregressed.
- D124 (port/src/gimgfixup.c): crash class C2 on Jungle. Compiled
  explosion-DL pointer-sync keyed on an IMAGESEG marker that texLoad()
  had already erased -> compiled globalDL_0xNNN arrays kept link-time
  IMAGESEG words -> 0xABCDxxxx into fast3d on first explosion draw.
  Latent on every level. Detect the slot from the compiled array instead.

Diagnosed, NOT fixed (write-ups in PCPortResearch.md SF):
- C2-GDL (D124-Facility addendum): Facility/Runway - model texture-pool
  path yields a garbage tex->data; every model file loads at an odd
  bank base (mempAllocBytesInBank does no alignment). Suspect
  d43_emit.py/pcmodels sidecar texture-blob offsets (N64 8B vs PC 16B Gfx).
- C3/C6 (D125): Aztec/Bunker2/Surface2 - converted propDefs blob in RAM
  doesn't match d88_propdefs.py offline output (garbage after record 0);
  runtime sizepropdef() walk drifts ~100 records -> wrong door/modelid.
  d88_propdefs.py convert_stream + sizepropdef() PORT strides verified
  correct; suspect a dest-offset/pd_end bug in d88_emit.py propdefs emit.

Remaining: 9 crashes / 6 classes (C2-GDL, C3/C6, C2m Jungle G_MTX,
C5 Control BG portal, C4 Depot BG tile/room, C7 Surface1 sndSetupSound).
Priority order in docs/LEVEL-STATUS.md.

Also folds in the in-progress docs restructure (HANDOFF/AGENTS/CLAUDE,
PCPortResearch D121/D122 SF/SH entries, PLAN-linear-level-sweep,
HANDOFF-ARCHIVE, BACKLOG).

docs/HANDOFF-switch-macro.md

@@ -1,3 +1,6 @@
+> **RESOLVED — historical.** D7/D8 closed at the compile+link milestone.
+> Kept for the IDO-vs-GCC preprocessor analysis. Not active work.
+
 # HANDOFF — SWITCH/CALL macro port (D7/D8) — IN PROGRESS
 
 ## Status: BLOCKED on SWITCH expansion mangling (root cause now fully understood)