conformance: migrate erlang onto shared driver (dict, 761/761 parity)

Erlang's suites load into one session and each exposes a pass counter plus a
*count* (total) counter rather than a fail counter, so MODE=dict fits directly:
each suite's runner is a dict literal {:passed P :failed (- count P) :total count}.
No driver change needed (dict mode already supports arbitrary runner expressions).
conformance.conf + 3-line shim; historical scoreboard schema preserved.

Parity verified 761/761 (0 fail), every suite matching baseline.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

plans/agent-briefings/conformance-loop.md

@@ -86,7 +86,7 @@ Blocked with specifics and move to the next candidate next iteration.
 ## Checklist
 
 - [x] common-lisp — migrated 487/487 (counters; driver extended for per-suite counters+preloads)
-- [ ] erlang
+- [x] erlang — migrated 761/761 (dict; pass/count → :failed = count-pass)
 - [ ] feed
 - [ ] forth
 - [ ] go
@@ -100,6 +100,12 @@ Blocked with specifics and move to the next candidate next iteration.
 
 ## Progress log (newest first)
 
+- 2026-06-07 — erlang: migrated to `MODE=dict`, 761/761 exact parity (tokenize 62,
+  parse 52, eval 408, runtime 93, ring 4, ping-pong 4, bank 8, echo 7, fib 8, ffi 37,
+  vm 78). Erlang exposes pass + *count* (total) counters, not pass/fail, so each suite's
+  dict-literal runner computes `:failed (- count pass)`. Loads in one session (matches
+  dict mode), so no driver change needed — only conformance.conf + shim. Kept historical
+  scoreboard schema (language/total_pass/total/suites[name,pass,total,status]).
 - 2026-06-07 — common-lisp: UNBLOCKED + migrated. Extended the shared driver's
   `MODE=counters` (lib/guest/conformance.sh) with a backward-compatible SUITES format
   `name:file[:pass-var:fail-var[:extra-preload ...]]` — optional per-suite counter