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>

internal/app/sasl.go

@@ -28,7 +28,7 @@ type SASLDB struct {
 
 // NewSASLDB builds a manager for the sasldb2 at path with the given realm. The
 // realm should match SELFPOST_HOSTNAME so the account identity lines up with
-// Postfix's SASL configuration in Phase 5.
+// Postfix's SASL configuration.
 func NewSASLDB(path, realm string) *SASLDB {
 	return &SASLDB{path: path, realm: realm, run: runSaslpasswd2, dump: dumpSASLDB}
 }