feat(notifications): producers — backups, agent health, scans, upgrades (#49)

* feat(filters): dynamic filter framework — typed schema, URL state, FilterBar

Port of dflow's filter.utils pattern, adapted to Containr:

- lib/dynamic-filter.ts: FilterConfig schema (search/select/multiselect/
  boolean/date-range/status), FilterEngine with client-side apply,
  derived options with counts, active-filter tracking, removal.
- lib/use-dynamic-filter.ts: filter state lives in ?f.<key> search
  params — filtered views are shareable links. useFilterState exposes
  URL state before data loads (server-backed filters); useDynamicFilter
  adds the engine over fetched data.
- shared/components/FilterBar.tsx: renders a schema as compact controls
  + active-filter chips, matching design tokens.
- Applied: audit logs (server-backed — state in URL, params to API),
  builds (server-backed + client date-range), activity (severity to the
  server query, category/search on the fetched page).
- 8 unit tests for the engine.

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Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

* fix(filters): erasableSyntaxOnly compat + BuildStatus cast

- Constructor parameter properties are banned under erasableSyntaxOnly —
  declare fields explicitly.
- listBuilds status param needs the BuildStatus type, not raw string.

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Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

* feat(notifications): producers round-out — backups, agent health, scans, upgrades

Four new emitters behind insertUserNotification:

- Backups: createBackupProcess notifies the database owner on
  completion (with size) and on failure (docker-down, snapshot error).
- Agent health: StartAgentHealthSweep marks agents offline after 3 min
  without heartbeat and back online on recovery — admins notified on
  each transition.
- Security scans: Scanner.OnScanComplete callback notifies the project
  owner with critical/high/total counts + score; scans with findings
  get a distinct title.
- Upgrades: daily check against the latest GitHub release; admins
  notified once per new tag (deduped via app_settings). Version stamped
  into the image via Dockerfile ARG + ldflags on tag builds; "dev"
  disables the check.

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---------

Co-authored-by: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

app/backend/internal/api/security.go

@@ -29,9 +29,27 @@ type SecurityHandler struct {
 func NewSecurityHandler(db *database.DB, encryptionKey string) *SecurityHandler {
 	encryptionManager, _ := security.NewEncryptionManager(encryptionKey)
 
+	scanner := security.NewScanner(db)
+	// Notify the project owner when a background scan completes — criticals
+	// earn a distinct title so they stand out in the notification list.
+	scanner.OnScanComplete = func(scan *security.SecurityScan) {
+		var ownerID string
+		if err := db.QueryRow(`SELECT owner_id::text FROM projects WHERE id = $1`, scan.ProjectID).Scan(&ownerID); err != nil || ownerID == "" {
+			return
+		}
+		title := "Security scan completed"
+		if scan.Summary.Critical > 0 || scan.Summary.High > 0 {
+			title = "Security scan found issues"
+		}
+		insertUserNotification(db, ownerID, "security", title,
+			fmt.Sprintf("%s scan finished: %d critical, %d high, %d total findings (score %d/100).",
+				scan.ScanType, scan.Summary.Critical, scan.Summary.High, scan.Summary.Total, scan.Summary.Score),
+			"project", scan.ProjectID)
+	}
+
 	return &SecurityHandler{
 		db:                   db,
-		scanner:              security.NewScanner(db),
+		scanner:              scanner,
 		complianceManager:    security.NewComplianceManager(db),
 		encryptionManager:    encryptionManager,
 		dataRetentionManager: security.NewDataRetentionManager(encryptionManager),