D291/D306: close Dam intro truck glitch as faithful; add repro probes

D291 (user-captured) is D306: Dam intro camera 5, truck over the walkway
camera; reproduces at FovScale 100. All PC-specific leads refuted with
evidence: FOV, depth precision/DrawDistance, depth state (every truck
triangle is opaque z-tested), near-plane handling, wheel transforms. The
image is a depth-correct view of the authored model from under the truck.
GE_ZF's earlier "real fighting" was a +-255 z quantisation artefact.

TEMP tools: GE_INTROCAM=<n> pins the level intro's first camera
(bondview_r.c, #ifdef PORT, PRNG draw still consumed); GE_D306C depth-state
census in gfx_pc.cpp. Golden gate 3/3.

docs/dev/GE-ENV-PROBES.md

@@ -68,6 +68,8 @@ Two classes:
 | `GE_D245_FIXEDSHIFT` | `src/game/sky.c:946` (`#ifdef PORT`) | D245 test override: pins the water tc shift `k` to the given integer (0..SKY_TC_MAX_SHIFT) instead of the computed per-vertex value, to A/B the allowShift=TRUE behavior. Off by default (unset = current behavior). | **live, test-only** (D245 OPEN) |
 | `GE_D252` | `port/fast3d/gfx_pc.cpp:733` (`import_texture`, cached `s_d252`) | D252 rainbow-particle diag: one-shot per (address,size) import log of the tile state (tmem/fmt/siz/addr/size/line) for small textures so a suspect particle tile can be checked against its source bytes by hand. Remove once D252 is resolved. | **live** (D252 OPEN — non-reproducible) |
 | `GE_D252POOL` | `src/game/image.c` (`texLoad`), `src/game/initmttex.c`, `port/src/gimgfixup.c` | **TEMP** (M-201): one line per new texture load (pool main/other, free bytes) + `POOL-FULL` events + stage pool range; `D252SYNC: N slots re-synced, M changed` per stage load (the D252 fix at work: M>0 from the 2nd stage on). Load-time only, no fps cost. | **TEMP** (D252 fixed; remove after release) |
+| `GE_D306C="f0 f1 [wmax]"` | `port/fast3d/gfx_pc.cpp` (after `zf_note_emit`) | **TEMP** (M-201): depth-state census of every emitted triangle in frames f0..f1 (GL depth mode, geometry_mode, other_mode_l, tile-0 texture, NDC centroid, z/w range, min w); optional `wmax` keeps near geometry only. Cap 60000 lines. | **TEMP** (D306 closed; remove post-release) |
+| `GE_INTROCAM=<n>` | `src/game/bondview_r.c` (`#ifdef PORT`, intro camera pick) | **TEMP/test-only**: force the level intro's first camera index (Dam truck shot = 5). The PRNG draw is still consumed. Logs `D306: intro camera index` when set (or with `GE_D306C`). | **TEMP** (useful repro tool) |
 | `GE_D235` | `src/boss.c` (per-stage `while (!done)` block, after `memaReset`; `#ifdef PORT`) | D235 evidence probe: logs how many GL-texture-cache entries the per-stage `videoResetTextureCache()` call purges at each level load. A cold boot into a level should log 0; a death/restart (or any transition from a level that uploaded textures) logs >0 — direct evidence of the stale-entry mechanism. The clear itself is **not** gated on this var (it's the fix, see below); the var only controls the log line. | **live** (D235) |
 | `GE_D235_OFF` | `src/boss.c` (same block) | **TEMP** A/B switch: skips the per-stage `videoResetTextureCache()`, i.e. reverts the D235 fix for one run. For comparing a restart with and without the fix. | **TEMP** (D235; remove when D235 closes) |
 | `GE_D235_RELOAD=<frames>` | `src/boss.c` (same block + `bossMainloop` retrace branch) | **TEMP** reload harness: once the title stage loads after the first level (e.g. after a scripted watch Abort), wait `<frames>` retraces, then re-enter that level via `bossSetLoadedStage()`, the front end's own mission-start call. A headless death/restart without the pointer-menu walk. Pair with `GE_INPUTSCRIPT="800:START;1200:A;1300:RIGHT;1400:A"` (abort) on `-level_XX`. | **TEMP** (D235; remove when D235 closes) |