docs(D255): consolidate real-Deck evidence - destroy-via-explosion, not activation

Further Steam Deck testing on the published v0.2.1 release reconciles
the two competing D255 repro theories: the trigger is an object dying
via explosion, not terminal activation. Confirmed on four levels:

- Facility: every terminal crashes consistently when destroyed
- Caverns: terminals near the radio objective crash when they explode
- Archives: a similar crash when a guard's grenade detonates (no
  terminal involved at all - narrows the real trigger to "object dies
  via explosion damage" in general)
- Frigate: negative control - shooting a room of terminals there did
  not reproduce it, so it isn't simply "any destructible OBJ record
  exploding" either

Updated the D255 finding with a static lead for the next session (the
objFree destroy path never explicitly nulls ObjectRecord.model, so the
NULL likely comes from a freed-slot-reuse or list-modify-during-iterate
race rather than a direct field write - untested, needs a live Deck
capture with the GE_D255 probes already in tree). Updated
.github/release-notes.md's D255 bullet to match.

.github/release-notes.md

@@ -143,12 +143,16 @@ Small hotfix batch from user playtest feedback on v0.2.0:
 - **Linux / Steam Deck: an intermittent SIGSEGV remains, with a reliable
   repro found this release** — Facility's computer terminals, the ones you
   activate to open a door for level progression, consistently crash the
-  game on activation (D255; not Deck-hardware-specific, seen on Linux
-  generally). Combat-related crashes reported earlier on Bunker/Frigate may
-  be the same underlying bug (an object record whose model reference goes
-  NULL while the record is still active for one more tick) via a different
-  trigger. We're tracking down the exact cause using the terminal repro;
-  please report any other Deck/Linux-specific faults.
+  game when destroyed (D255; not Deck-hardware-specific, seen on Linux
+  generally). Confirmed on real Steam Deck hardware across multiple levels:
+  every terminal on Facility, terminals near the radio objective on
+  Caverns, and a similar crash on Archives when a guard's grenade
+  detonates — all point at the same underlying bug (an object record whose
+  model reference goes NULL while the record is still active for one more
+  tick), triggered by an object exploding/being destroyed rather than by
+  simple interaction. Not (yet) reproduced by shooting a room of terminals
+  on Frigate, so the trigger isn't purely "destroy any terminal" — still
+  under investigation. Please report any other Deck/Linux-specific faults.
 - **Steam Deck / gamepad: the right analog stick currently navigates the
   main menu, file select, and mission-select map** — not the left stick.
   This matches the N64 default but is unintuitive on a modern controller;