identity: membership state machine + per-app grant projection (17 tests)

membership.sx — coop membership as a guarded state machine
(none→pending→active→lapsed⇄active, any→revoked terminal); invalid
transitions return explicit {error, CurrentStatus}, never silent no-ops.
project(Subject, App) renders the one canonical state into a per-app claim
({member,Tier,App} / {pending,App} / {lapsed,App} / {denied,App} /
{non_member,App}) — identity reports what the membership is; acl decides
whether the app should honour it. New tests/membership.sx. 92/92.

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

lib/identity/conformance.sh

@@ -34,6 +34,7 @@ SUITES=(
   "api|id-api-test-pass|id-api-test-count"
   "oauth|id-oauth-test-pass|id-oauth-test-count"
   "sso|id-sso-test-pass|id-sso-test-count"
+  "membership|id-membership-test-pass|id-membership-test-count"
 )
 
 cat > "$TMPFILE" << 'EPOCHS'
@@ -50,12 +51,14 @@ cat > "$TMPFILE" << 'EPOCHS'
 (load "lib/identity/registry.sx")
 (load "lib/identity/api.sx")
 (load "lib/identity/oauth.sx")
+(load "lib/identity/membership.sx")
 (load "lib/identity/tests/session.sx")
 (load "lib/identity/tests/token.sx")
 (load "lib/identity/tests/registry.sx")
 (load "lib/identity/tests/api.sx")
 (load "lib/identity/tests/oauth.sx")
 (load "lib/identity/tests/sso.sx")
+(load "lib/identity/tests/membership.sx")
 (epoch 100)
 (eval "(list id-session-test-pass id-session-test-count)")
 (epoch 101)
@@ -68,6 +71,8 @@ cat > "$TMPFILE" << 'EPOCHS'
 (eval "(list id-oauth-test-pass id-oauth-test-count)")
 (epoch 105)
 (eval "(list id-sso-test-pass id-sso-test-count)")
+(epoch 106)
+(eval "(list id-membership-test-pass id-membership-test-count)")
 EPOCHS
 
 timeout 600 "$SX_SERVER" < "$TMPFILE" > "$OUTFILE" 2>&1