release: 1.9.2: Review pass: port-25 milters, DMARC validation, rate-limit fix

Review pass over `1.4.0`…`1.9.1`: port 25 no longer shares the submission milter chain, DMARC reports are validated before they are stored, and the auto rate limit is correct for a non-default level-1 window. Schema migration `0010` (index only). Upgrading is a tag bump.
Added:
  - SQLite migration `0010_send_log_app_login_index.sql` —
  - DMARC aggregate reports are accepted as **zip** as well as gzip or plain XML
  - e2e: `checkPort25ConfigCombinations` regenerates the Postfix configuration
Changed:
  - README hero line and a **Positioning** block in `docs/product.md` record the
Fixed:
  - The setup account's password is hashed at bcrypt cost `12` like every other
  - Login/setup rate limiter: protecting blocked buckets from eviction is now
  - `postqueue -p` output is bounded to 4 MiB (the timeout alone left the size of
  - [schema-migrations.md](docs/schema-migrations.md): the schema section was
  - postqueue reader is now time-bounded: `postqueue -p` runs under a 5-second
  … (11 more in CHANGELOG)
Changed:
  - [roadmap.md](docs/roadmap.md) now carries everything the 2026-08-19 code
  - Extracted `internal/configsafe` — the empty-value and forbidden-character
  - Build, deploy and migration comments no longer cite the archived
  - Dropped the `parseDomainRateLimitForm` / `parseAppRateLimitForm` pass-through
  - Extracted shared helpers: `internal/atomicfile` (atomic temp-write+rename) and
  … (7 more in CHANGELOG)
Removed:
  - Unused legacy asset `docs/assets/icon.png` (superseded by the four brand SVGs
  - Plan documents for already-shipped features: `domain-stats-auto-ratelimit`,

Full detail: CHANGELOG.md (1.9.2).

internal/supervisor/supervisor.go

@@ -0,0 +1,36 @@
+// Package supervisor provides helpers for controlling processes through
+// supervisord's control socket (architecture.md, security.md).
+package supervisor
+
+import (
+	"fmt"
+	"os/exec"
+	"strings"
+)
+
+const confPath = "/etc/supervisor/supervisord.conf"
+
+// Start issues a `supervisorctl start` for the named program. A program that
+// is already running is not an error (the pending run covers the caller's
+// intent).
+func Start(program string) error {
+	cmd := exec.Command("supervisorctl", "-c", confPath, "start", program)
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		if strings.Contains(string(out), "already started") {
+			return nil
+		}
+		return fmt.Errorf("supervisor start %s: %w: %s", program, err, strings.TrimSpace(string(out)))
+	}
+	return nil
+}
+
+// Signal sends a signal to a supervised program via `supervisorctl signal`.
+func Signal(sig, program string) error {
+	cmd := exec.Command("supervisorctl", "-c", confPath, "signal", sig, program)
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		return fmt.Errorf("supervisor signal %s %s: %w: %s", sig, program, err, strings.TrimSpace(string(out)))
+	}
+	return nil
+}