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/web/security_test.go

@@ -32,7 +32,7 @@ func post(secFetchSite, origin string) *http.Request {
 	return r
 }
 
-// The full matrix the origin check has to get right (phase 14.A). The row that
+// The full matrix the origin check has to get right. The row that
 // matters most is "same-site": a neighbouring host on example.com is same-site
 // as far as the session cookie's SameSite=Lax is concerned, so this check is
 // the only thing standing between it and a forged POST.