docs/chore: Phase 1 doc/code hygiene (code-review.md § Phase 1)

Removes ~30 stale "Phase N" / historical-staging comment references from
code and shell scripts now that v1.0 is done; fixes a stale dashboard
comment claiming applications/send-log were unimplemented; adds a CSRF ADR
to security.md documenting the Origin-check-over-tokens decision; resolves
docs/logo in roadmap.md (directory doesn't exist, criterion already met);
adds a gofmt -l check to CI so unformatted Go fails the build.

The known-limitations write-up for the log-tailer offset gap (the other
Phase 1 item) was already present in architecture.md § Log tailer, so no
change was needed there.

gofmt/go vet/go test clean on both Go modules (main + test/e2e), verified
on the dev server.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

build/postfix-wrapper.sh

@@ -8,7 +8,7 @@
 # an explicit startup failure instead of a relay running blind.
 #
 # This handles cold start only. Runtime milter failures after a successful start
-# are governed by fail-open (milter_default_action), configured in Phase 5.
+# are governed by fail-open (milter_default_action).
 set -eu
 
 OPENDKIM_SOCK="${OPENDKIM_SOCKET:-/run/opendkim/opendkim.sock}"