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).

CLAUDE.md

@@ -6,13 +6,34 @@ checklists that were being skipped.
 
 @AGENTS.md
 
+## Doc load order — read deliberately, not everything
+
+Context is scarce. Load by tier; do not blind-read whole files.
+
+- **Tier 0 — always (auto-loaded):** `CLAUDE.md`, `AGENTS.md`. Nothing
+  else auto-loads.
+- **Tier 1 — every session start, read fully (both are short):**
+  `docs/HANDOFF.md` (current state + next task + environment),
+  `docs/PORT-LEARNINGS.md` (recurring bug classes).
+- **Tier 2 — on demand only, do NOT read start-to-finish:**
+  - `docs/PCPortResearch.md` §1–§10 — architecture / RSP deltas / phased
+    plan. Read the section you need.
+  - `docs/PCPortResearch.md` §F + §H — the Dxx finding log. **Jump to a
+    specific `Dxx` via the index at the top of §F.** Never linear-read.
+  - `docs/HANDOFF-ARCHIVE.md` — prior-session narrative (M-2…). Only when
+    tracing the history of one fix.
+  - `docs/AGENT-WORKFLOW.md` — before dispatching a subagent (also Tier 1
+    if you may dispatch this session).
+  - `docs/PLAN-linear-level-sweep.md` — the active plan of record.
+
 ## Session preflight — do this in your FIRST few tool calls, before acting
 
 Having a concrete "next step" from the handoff is NOT license to skip this.
 
-1. Read `docs/HANDOFF.md` — immediate task, standing procedure, environment gotchas.
-2. Read `docs/PORT-LEARNINGS.md` — recurring bug classes (you will re-derive
-   bugs already catalogued here if you don't).
+1. Read the Tier 1 docs: `docs/HANDOFF.md` (immediate task, standing
+   procedure, environment gotchas) and `docs/PORT-LEARNINGS.md`
+   (recurring bug classes — you will re-derive catalogued bugs if you don't).
+2. Skim `docs/PLAN-linear-level-sweep.md` — the active plan of record.
 3. If you may dispatch a subagent this session, read `docs/AGENT-WORKFLOW.md`
    NOW — not at dispatch time.