panel-redesign: the 2.0 schema from zero - one baseline, no 1.x chain

Stage 1, step 1. BREAKING: a 1.x database is not migrated.

Schema
  - internal/store/migrations/ holds one file, 0001_init.sql, equal to the
    2.0 schema; 0002..0010 are deleted (they stay in history at 1.9.5). No
    admin table created and dropped, no ALTERs.
  - users.email replaces users.dmarc_report_email: the address is the
    user's own. The default DMARC report address is a user's setting
    (dmarc_default_mode hosted/account/custom/none, dmarc_default_address);
    the instance setting that mirrored the global user's field is gone.
  - domains.dmarc_rua_user_id: a domain follows a named user's default, or
    has an address of its own in dmarc_rua ('' = none). ON DELETE SET NULL
    leaves it at "no reports", never at someone else's default.
  - user_inbound_domains, users.all_domains, users.all_inbound_domains: in
    the schema for the inbound delegation of the next step.
  - users.role is 'global' / 'domain' (was 'domain_admin');
    rate_limits.allowed_ips, unused since 1.9.0, is dropped.

Opening a database
  - The baseline sets PRAGMA application_id ("SP20"). store.Open refuses a
    file that has a schema version without it (ErrForeignSchema) and one
    newer than the build. A 1.x file at user_version 10 would otherwise read
    as already migrated. The refused file is left untouched.

Code
  - Store.DomainDMARCRua is the one place a domain's report address is
    resolved; dnscheck.ResolveDMARCRua and Store.GlobalDMARCReportEmail are
    gone. dmarc.AllowedRecipients, the domain page, the dashboard and the
    DNS re-check go through it.
  - The old templates keep working on the new model until their pages are
    restyled: the Settings form's address field is the account e-mail and
    switches the user's default between it and none; a domain's "Same as
    Settings" makes it follow the user who chose it; a new or imported
    domain follows its creator.
  - Domain export/import: a domain that follows a user exports no address.

Tests: the baseline pinned table by table (TestBaselineSchema), refusal of a
1.x and of a newer database, constraints and cascades of the new columns and
table, resolution in every default mode, the deleted-user case, and the three
bridged handlers.

docs/schema-migrations.md is rewritten for the baseline; roadmap 11/27,
schema-squash marked built.

go test ./...   (Windows)
  ok for every package except two that fail the same way before this commit:
  internal/domain  TestWriteLoadPrivateKeyRoundtrip (file mode on NTFS)
  internal/logtail TestFollowTailsAndRotates (rename of an open file)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/web/handlers/handlers_settings.go

@@ -30,7 +30,7 @@ func (h *Handlers) HandleSettings(w http.ResponseWriter, r *http.Request) {
 			http.Error(w, "internal error", http.StatusInternalServerError)
 			return
 		}
-		h.renderSettings(w, r, http.StatusOK, "", u.Username, u.DMARCReportEmail, h.sendLogRetentionDays(), p.IsGlobal())
+		h.renderSettings(w, r, http.StatusOK, "", u.Username, u.Email, h.sendLogRetentionDays(), p.IsGlobal())
 	case http.MethodPost:
 		h.submitSettings(w, r)
 	default:
@@ -128,7 +128,7 @@ func (h *Handlers) submitSettings(w http.ResponseWriter, r *http.Request) {
 	dmarcEmail := strings.TrimSpace(r.PostFormValue("dmarc_report_email"))
 	formRetention := currentRetention
 	if !p.IsGlobal() {
-		dmarcEmail = user.DMARCReportEmail
+		dmarcEmail = user.Email
 	} else if raw := strings.TrimSpace(r.PostFormValue("send_log_retention_days")); raw != "" {
 		parsed, err := strconv.Atoi(raw)
 		if err != nil {
@@ -161,7 +161,7 @@ func (h *Handlers) submitSettings(w http.ResponseWriter, r *http.Request) {
 		}
 	}
 
-	emailChanging := p.IsGlobal() && dmarcEmail != user.DMARCReportEmail
+	emailChanging := p.IsGlobal() && dmarcEmail != user.Email
 
 	retentionChanging := false
 	if p.IsGlobal() && formRetention != currentRetention {
@@ -218,6 +218,23 @@ func (h *Handlers) submitSettings(w http.ResponseWriter, r *http.Request) {
 		}
 	}
 
+	// Until the Account page replaces this form (stage 2), its one "default
+	// report address" field stands for both halves of the 2.0 model: it is the
+	// account e-mail, and the user's DMARC default is "my account e-mail" while
+	// it is filled and "none" once it is cleared.
+	if emailChanging {
+		mode := store.DMARCDefaultNone
+		if dmarcEmail != "" {
+			mode = store.DMARCDefaultAccount
+		}
+		if err := h.store.SetDMARCDefault(user.ID, mode, ""); err != nil {
+			logf("panel: settings: set dmarc default failed: %v", err)
+			h.renderSettings(w, r, http.StatusInternalServerError,
+				"Could not save the changes. Please check the logs and try again.", username, dmarcEmail, formRetention, p.IsGlobal())
+			return
+		}
+	}
+
 	if retentionChanging {
 		if err := h.store.SetSendLogRetentionDays(formRetention); err != nil {
 			logf("panel: settings: set send-log retention failed: %v", err)