Convert backend from submodule to regular directory

Remove submodule tracking; backend is now a plain directory in the repo.
Also update deploy workflow: remove --recurse-submodules.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/internal/db/suggestions.go

@@ -0,0 +1,54 @@
+package db
+
+import (
+	"context"
+
+	"github.com/jackc/pgx/v5"
+	"github.com/jackc/pgx/v5/pgxpool"
+
+	"github.com/jacek/pamietnik/backend/internal/domain"
+)
+
+type SuggestionStore struct {
+	pool *pgxpool.Pool
+}
+
+func NewSuggestionStore(pool *pgxpool.Pool) *SuggestionStore {
+	return &SuggestionStore{pool: pool}
+}
+
+func (s *SuggestionStore) ListByDate(ctx context.Context, userID, date string) ([]domain.Suggestion, error) {
+	rows, err := s.pool.Query(ctx, `
+		SELECT sg.suggestion_id, sg.stop_id, sg.type, sg.title, sg.text,
+		       sg.created_at, sg.dismissed_at
+		FROM suggestions sg
+		JOIN stops st ON st.stop_id = sg.stop_id
+		JOIN devices d ON d.device_id = st.device_id
+		WHERE d.user_id = $1
+		  AND DATE(st.start_ts AT TIME ZONE 'UTC') = $2::date
+		ORDER BY sg.created_at`,
+		userID, date,
+	)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	return pgx.CollectRows(rows, func(row pgx.CollectableRow) (domain.Suggestion, error) {
+		var sg domain.Suggestion
+		err := row.Scan(
+			&sg.SuggestionID, &sg.StopID, &sg.Type, &sg.Title, &sg.Text,
+			&sg.CreatedAt, &sg.DismissedAt,
+		)
+		return sg, err
+	})
+}
+
+func (s *SuggestionStore) Insert(ctx context.Context, sg domain.Suggestion) error {
+	_, err := s.pool.Exec(ctx, `
+		INSERT INTO suggestions (suggestion_id, stop_id, type, title, text, created_at)
+		VALUES ($1,$2,$3,$4,$5,$6)
+		ON CONFLICT (suggestion_id) DO NOTHING`,
+		sg.SuggestionID, sg.StopID, sg.Type, sg.Title, sg.Text, sg.CreatedAt,
+	)
+	return err
+}