test(conformance): raise idempotency timeout for the full corpus

With the corpus un-skipped, all 9 Ready-gated entries now run (each ~3 min:
Ready + 10x reconcile-fingerprint pokes). The previous 30m `go test` timeout was
just under the total, so the run panicked mid-corpus after 7 entries had already
passed (minimal, maximal, gateways-all, selfconfig, profilestore, autoupdate,
backup all reached Ready + held idempotency). Raise the go-test timeout to 55m
and the Idempotency job to 65m so the full corpus completes.

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

Author: stubbi

.github/workflows/conformance.yaml

@@ -42,7 +42,7 @@ jobs:
   idempotency:
     name: Idempotency
     runs-on: ubuntu-latest
-    timeout-minutes: 45
+    timeout-minutes: 65
     steps:
       - uses: actions/checkout@v6
       - uses: actions/setup-go@v6

Makefile

@@ -359,7 +359,7 @@ conformance-negative:
 
 .PHONY: conformance-idempotency
 conformance-idempotency:
-	cd test/conformance && go test -v -timeout 30m -ginkgo.v -ginkgo.focus="idempotency" ./...
+	cd test/conformance && go test -v -timeout 55m -ginkgo.v -ginkgo.focus="idempotency" ./...
 
 .PHONY: conformance-upgrade
 conformance-upgrade: