fix(cdb): A6.P1 — v1 dry-run lessons + v2 prep tooling

Dry-run of scenario 1 (retail-v1-broken-offsets.log preserved as
audit trail) surfaced three issues with the v1 cdb script:

1. STACK-ARG OFFSETS WRONG: BP actions used arbitrary registers
   (@edx, @edi) to read function args, but __thiscall puts non-this
   args on the stack ([esp+N] after the return address). All 12 BP5
   "adjust_sphere" hits printed Nx=0.0 Ny=0.0 ... — fields not read.
   Fixed by writing a type dumper (a6-types-dump.cdb + runner) that
   uses cdb's `dt` command against the loaded PDB to get authoritative
   struct offsets. v2 probe script (to be written next) will use
   double-indirect reads (dwo(poi(@esp+N)+offset)) with correct
   offsets from the dump.

2. TEE-OBJECT UTF-16 ENCODING: PowerShell's default Tee-Object writes
   UTF-16 LE with BOM, making logs unparseable by grep without
   conversion. Runner now uses Out-File -Encoding ASCII. Sacrifices
   live console echo; use `Get-Content -Tail 50 -Wait` in a separate
   shell if live monitoring is needed.

3. BP6 SYMBOL NOT FOUND: `acclient!CTransition::validate_walkable`
   doesn't exist in the PDB. Decomp at line 272811 has
   `CTransition::check_walkable` — likely the actual name. To be
   verified + fixed in v2.

The BP hit-count distribution from v1 is still meaningful diagnostic
data (14,318 transitional_insert + 16,558 find_collisions + 40
set_contact_plane + 12 adjust_sphere + 1 step_up + 1 set_collide in
a 2-second walk through the inn doorway). Preserved as a baseline
sanity-check the v2 distribution can be diffed against.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tools/cdb/a6-types-dump.cdb

@@ -0,0 +1,50 @@
+$$
+$$ Phase A6.P1 type dumper — authoritative struct offsets from PDB
+$$
+$$ Dumps the layouts of the 6 retail types A6's probe BPs need to read:
+$$   - CPolygon (BP5 — adjust_sphere_to_plane)
+$$   - CSphere (BP5)
+$$   - Plane (BP5, BP7)
+$$   - SPHEREPATH (BP2, BP3, BP5, BP6)
+$$   - CTransition (BP1, BP2, BP6)
+$$   - COLLISIONINFO (BP7)
+$$   - Position (containing struct in several of the above)
+$$   - OBJECTINFO (BP2 — walkable_z)
+$$
+$$ No breakpoints. Just dt + qd. Run once before authoring v2 probe.
+$$ Usage: .\tools\cdb\a6-types-dump-runner.ps1
+$$
+
+.sympath C:\Users\erikn\source\repos\acdream\refs
+.symopt+ 0x40
+.reload /f acclient.exe
+
+.printf "\n===== Type dump for A6.P1 cdb script offset derivation =====\n\n"
+
+.printf "=== Plane ===\n"
+dt -v acclient!Plane
+
+.printf "\n=== CSphere ===\n"
+dt -v acclient!CSphere
+
+.printf "\n=== Position ===\n"
+dt -v acclient!Position
+
+.printf "\n=== CPolygon ===\n"
+dt -v acclient!CPolygon
+
+.printf "\n=== SPHEREPATH ===\n"
+dt -v acclient!SPHEREPATH
+
+.printf "\n=== CTransition ===\n"
+dt -v acclient!CTransition
+
+.printf "\n=== COLLISIONINFO ===\n"
+dt -v acclient!COLLISIONINFO
+
+.printf "\n=== OBJECTINFO ===\n"
+dt -v acclient!OBJECTINFO
+
+.printf "\n===== Done =====\n"
+
+qd