Initial implementation of inventree

A small IT asset inventory system built around a nested folder tree,
matching the project brief: Go + html/template + Bootstrap 5 + vanilla JS,
SQLite storage (WAL, FKs, migrations), embedded templates/static assets,
single compiled binary.

- AJAX-driven inventory tree: lazy-loaded folder expansion with per-user
  persisted expand state, drag-and-drop move for folders/assets, safe
  delete-with-relocate-or-cascade confirmation, search with breadcrumbs.
- Assets: CRUD, duplicate, move, auto-generated IT-000001-style IDs,
  CSV import (with optional folder auto-create) and export.
- Admin-defined item types with custom fields (text/long_text/number/date/
  boolean/dropdown/url/ip_address).
- Configurable statuses, session-based auth (bcrypt, secure cookies),
  admin/user roles, user management.
- CLI: serve, version, database migrate, database backup; /healthz;
  graceful shutdown; Dockerfile/docker-compose/systemd unit; Go test suite.

internal/database/database.go

@@ -0,0 +1,124 @@
+// Package database manages the SQLite connection and schema migrations.
+package database
+
+import (
+	"database/sql"
+	"embed"
+	"fmt"
+	"io/fs"
+	"log/slog"
+	"path/filepath"
+	"sort"
+	"strings"
+
+	_ "modernc.org/sqlite"
+)
+
+//go:embed migrations/*.sql
+var migrationsFS embed.FS
+
+// Open opens the SQLite database at path, applies pragmas suited for a
+// concurrent web application, and runs any pending migrations.
+func Open(path string) (*sql.DB, error) {
+	dsn := fmt.Sprintf("file:%s?_pragma=busy_timeout(5000)", path)
+	db, err := sql.Open("sqlite", dsn)
+	if err != nil {
+		return nil, fmt.Errorf("open database: %w", err)
+	}
+
+	// SQLite only supports one writer at a time; a single connection avoids
+	// SQLITE_BUSY under concurrent goroutines while WAL still allows
+	// concurrent readers.
+	db.SetMaxOpenConns(1)
+
+	pragmas := []string{
+		"PRAGMA journal_mode = WAL",
+		"PRAGMA foreign_keys = ON",
+		"PRAGMA synchronous = NORMAL",
+		"PRAGMA busy_timeout = 5000",
+	}
+	for _, p := range pragmas {
+		if _, err := db.Exec(p); err != nil {
+			db.Close()
+			return nil, fmt.Errorf("set pragma %q: %w", p, err)
+		}
+	}
+
+	if err := Migrate(db); err != nil {
+		db.Close()
+		return nil, fmt.Errorf("migrate: %w", err)
+	}
+
+	return db, nil
+}
+
+// Migrate applies any migrations that have not yet been recorded in the
+// schema_migrations table, in filename order, each inside its own
+// transaction.
+func Migrate(db *sql.DB) error {
+	if _, err := db.Exec(`CREATE TABLE IF NOT EXISTS schema_migrations (
+		version    TEXT PRIMARY KEY,
+		applied_at TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%fZ', 'now'))
+	)`); err != nil {
+		return fmt.Errorf("create schema_migrations: %w", err)
+	}
+
+	applied := map[string]bool{}
+	rows, err := db.Query(`SELECT version FROM schema_migrations`)
+	if err != nil {
+		return fmt.Errorf("query schema_migrations: %w", err)
+	}
+	for rows.Next() {
+		var v string
+		if err := rows.Scan(&v); err != nil {
+			rows.Close()
+			return err
+		}
+		applied[v] = true
+	}
+	if err := rows.Err(); err != nil {
+		return err
+	}
+	rows.Close()
+
+	entries, err := fs.ReadDir(migrationsFS, "migrations")
+	if err != nil {
+		return fmt.Errorf("read migrations dir: %w", err)
+	}
+	var names []string
+	for _, e := range entries {
+		if !e.IsDir() && strings.HasSuffix(e.Name(), ".sql") {
+			names = append(names, e.Name())
+		}
+	}
+	sort.Strings(names)
+
+	for _, name := range names {
+		if applied[name] {
+			continue
+		}
+		content, err := fs.ReadFile(migrationsFS, filepath.Join("migrations", name))
+		if err != nil {
+			return fmt.Errorf("read migration %s: %w", name, err)
+		}
+
+		tx, err := db.Begin()
+		if err != nil {
+			return fmt.Errorf("begin tx for %s: %w", name, err)
+		}
+		if _, err := tx.Exec(string(content)); err != nil {
+			tx.Rollback()
+			return fmt.Errorf("apply migration %s: %w", name, err)
+		}
+		if _, err := tx.Exec(`INSERT INTO schema_migrations (version) VALUES (?)`, name); err != nil {
+			tx.Rollback()
+			return fmt.Errorf("record migration %s: %w", name, err)
+		}
+		if err := tx.Commit(); err != nil {
+			return fmt.Errorf("commit migration %s: %w", name, err)
+		}
+		slog.Info("applied migration", "name", name)
+	}
+
+	return nil
+}