Add cookie banner versioning with JSONB snapshots

Introduce append-only cookie_banner_versions table with a JSONB
snapshot of consent-relevant configuration (privacy policy URL,
consent mode, expiry, categories and their cookies). Each version
has its own state (DRAFT/PUBLISHED) separate from the banner
lifecycle.

Replace the banner state enum (DRAFT/PUBLISHED/DISABLED) with a
simpler ACTIVE/INACTIVE toggle. Link consent records to the
specific published version the visitor accepted.

Signed-off-by: Émile Ré <emile@getprobo.com>

pkg/coredata/cookie_banner_version_state.go

@@ -0,0 +1,70 @@
+// Copyright (c) 2026 Probo Inc <hello@getprobo.com>.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+package coredata
+
+import (
+	"database/sql/driver"
+	"fmt"
+)
+
+type CookieBannerVersionState string
+
+const (
+	CookieBannerVersionStateDraft     CookieBannerVersionState = "DRAFT"
+	CookieBannerVersionStatePublished CookieBannerVersionState = "PUBLISHED"
+)
+
+func CookieBannerVersionStates() []CookieBannerVersionState {
+	return []CookieBannerVersionState{
+		CookieBannerVersionStateDraft,
+		CookieBannerVersionStatePublished,
+	}
+}
+
+func (s CookieBannerVersionState) String() string {
+	return string(s)
+}
+
+func (s *CookieBannerVersionState) Scan(value any) error {
+	var v string
+	switch val := value.(type) {
+	case string:
+		v = val
+	case []byte:
+		v = string(val)
+	default:
+		return fmt.Errorf("unsupported type for CookieBannerVersionState: %T", value)
+	}
+
+	switch CookieBannerVersionState(v) {
+	case CookieBannerVersionStateDraft:
+		*s = CookieBannerVersionStateDraft
+	case CookieBannerVersionStatePublished:
+		*s = CookieBannerVersionStatePublished
+	default:
+		return fmt.Errorf("invalid CookieBannerVersionState value: %q", v)
+	}
+	return nil
+}
+
+func (s CookieBannerVersionState) Value() (driver.Value, error) {
+	switch s {
+	case CookieBannerVersionStateDraft,
+		CookieBannerVersionStatePublished:
+		return string(s), nil
+	default:
+		return nil, fmt.Errorf("invalid CookieBannerVersionState: %s", s)
+	}
+}