feat(121+122): smsplanet conversation, notifications, default footer

Phase 121 — SMSPLANET Conversation + Notifications:
- migration 20260512_000110 adds smsplanet conversation + notifications tables
- src/Modules/Sms (SmsConversationService, SmsMessageRepository, SmsplanetWebhookController)
- src/Modules/Notifications (Repository, Controller, ApiController)
- order SMS tab, notification center, sender mode, inbound webhook
- public notifications.js + layouts/app.php integration

Phase 122 — SMSPLANET Default SMS Footer:
- migration 20260512_000111 adds smsplanet_integration_settings.default_footer
- footer appended to test SMS and order SMS, validated against 918 char limit
- settings textarea + compact order SMS note when footer configured

Bundled (could not split per-phase without hunk staging):
- routes/web.php (also carries Phase 118 fakturownia redirects)
- DOCS/{ARCHITECTURE,DB_SCHEMA,TECH_CHANGELOG}.md (118 + 121 + 122 entries)
- .paul/codebase/{architecture,db_schema,tech_changelog}.md (118 + 121 + 122)
- .paul/STATE.md, ROADMAP.md, changelog/2026-05-12.md (UNIFY closure)

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

database/migrations/20260512_000111_smsplanet_default_footer.sql

@@ -0,0 +1,13 @@
+SET @smsplanet_default_footer_exists = (
+    SELECT COUNT(*)
+    FROM information_schema.COLUMNS
+    WHERE TABLE_SCHEMA = DATABASE()
+      AND TABLE_NAME = 'smsplanet_integration_settings'
+      AND COLUMN_NAME = 'default_footer'
+);
+SET @sql = IF(@smsplanet_default_footer_exists = 0,
+    'ALTER TABLE smsplanet_integration_settings ADD COLUMN default_footer TEXT NULL AFTER transactional',
+    'SELECT ''default_footer already exists''');
+PREPARE stmt FROM @sql;
+EXECUTE stmt;
+DEALLOCATE PREPARE stmt;