feat: add CPU and memory resource limits per app

- Add cpu_limit (REAL) and memory_limit (INTEGER) columns to apps table
  via migration 007
- Add CPULimit and MemoryLimit fields to App model with full CRUD support
- Add resource limits fields to app edit form with human-friendly
  memory input (e.g. 256m, 1g, 512k)
- Pass CPU and memory limits to Docker container creation via
  NanoCPUs and Memory host config fields
- Extract Docker container creation helpers (buildEnvSlice, buildMounts,
  buildResources) for cleaner code
- Add formatMemoryBytes template function for display
- Add comprehensive tests for parsing, formatting, model persistence,
  and container options

internal/handlers/resource_limits_test.go

@@ -0,0 +1,195 @@
+package handlers //nolint:testpackage // tests unexported parsing functions
+
+import (
+	"database/sql"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestParseOptionalFloat64(t *testing.T) {
+	t.Parallel()
+
+	t.Run("empty string returns invalid", func(t *testing.T) {
+		t.Parallel()
+
+		result, err := parseOptionalFloat64("")
+		require.NoError(t, err)
+		assert.False(t, result.Valid)
+	})
+
+	t.Run("whitespace only returns invalid", func(t *testing.T) {
+		t.Parallel()
+
+		result, err := parseOptionalFloat64("   ")
+		require.NoError(t, err)
+		assert.False(t, result.Valid)
+	})
+
+	t.Run("valid float", func(t *testing.T) {
+		t.Parallel()
+
+		result, err := parseOptionalFloat64("0.5")
+		require.NoError(t, err)
+		assert.True(t, result.Valid)
+		assert.InDelta(t, 0.5, result.Float64, 0.001)
+	})
+
+	t.Run("valid integer", func(t *testing.T) {
+		t.Parallel()
+
+		result, err := parseOptionalFloat64("2")
+		require.NoError(t, err)
+		assert.True(t, result.Valid)
+		assert.InDelta(t, 2.0, result.Float64, 0.001)
+	})
+
+	t.Run("negative value rejected", func(t *testing.T) {
+		t.Parallel()
+
+		_, err := parseOptionalFloat64("-1")
+		require.Error(t, err)
+	})
+
+	t.Run("zero value rejected", func(t *testing.T) {
+		t.Parallel()
+
+		_, err := parseOptionalFloat64("0")
+		require.Error(t, err)
+	})
+
+	t.Run("non-numeric rejected", func(t *testing.T) {
+		t.Parallel()
+
+		_, err := parseOptionalFloat64("abc")
+		require.Error(t, err)
+	})
+}
+
+func TestParseOptionalMemoryBytes(t *testing.T) { //nolint:funlen // table-driven test
+	t.Parallel()
+
+	t.Run("empty string returns invalid", func(t *testing.T) {
+		t.Parallel()
+
+		result, err := parseOptionalMemoryBytes("")
+		require.NoError(t, err)
+		assert.False(t, result.Valid)
+	})
+
+	t.Run("whitespace only returns invalid", func(t *testing.T) {
+		t.Parallel()
+
+		result, err := parseOptionalMemoryBytes("   ")
+		require.NoError(t, err)
+		assert.False(t, result.Valid)
+	})
+
+	t.Run("plain bytes", func(t *testing.T) {
+		t.Parallel()
+
+		result, err := parseOptionalMemoryBytes("536870912")
+		require.NoError(t, err)
+		assert.True(t, result.Valid)
+		assert.Equal(t, int64(536870912), result.Int64)
+	})
+
+	t.Run("megabytes suffix", func(t *testing.T) {
+		t.Parallel()
+
+		result, err := parseOptionalMemoryBytes("256m")
+		require.NoError(t, err)
+		assert.True(t, result.Valid)
+		assert.Equal(t, int64(256*1024*1024), result.Int64)
+	})
+
+	t.Run("megabytes suffix uppercase", func(t *testing.T) {
+		t.Parallel()
+
+		result, err := parseOptionalMemoryBytes("256M")
+		require.NoError(t, err)
+		assert.True(t, result.Valid)
+		assert.Equal(t, int64(256*1024*1024), result.Int64)
+	})
+
+	t.Run("gigabytes suffix", func(t *testing.T) {
+		t.Parallel()
+
+		result, err := parseOptionalMemoryBytes("1g")
+		require.NoError(t, err)
+		assert.True(t, result.Valid)
+		assert.Equal(t, int64(1024*1024*1024), result.Int64)
+	})
+
+	t.Run("kilobytes suffix", func(t *testing.T) {
+		t.Parallel()
+
+		result, err := parseOptionalMemoryBytes("512k")
+		require.NoError(t, err)
+		assert.True(t, result.Valid)
+		assert.Equal(t, int64(512*1024), result.Int64)
+	})
+
+	t.Run("fractional gigabytes", func(t *testing.T) {
+		t.Parallel()
+
+		result, err := parseOptionalMemoryBytes("1.5g")
+		require.NoError(t, err)
+		assert.True(t, result.Valid)
+		assert.Equal(t, int64(1.5*1024*1024*1024), result.Int64)
+	})
+
+	t.Run("negative value rejected", func(t *testing.T) {
+		t.Parallel()
+
+		_, err := parseOptionalMemoryBytes("-256m")
+		require.Error(t, err)
+	})
+
+	t.Run("zero value rejected", func(t *testing.T) {
+		t.Parallel()
+
+		_, err := parseOptionalMemoryBytes("0")
+		require.Error(t, err)
+	})
+
+	t.Run("invalid string rejected", func(t *testing.T) {
+		t.Parallel()
+
+		_, err := parseOptionalMemoryBytes("abc")
+		require.Error(t, err)
+	})
+
+	t.Run("negative plain bytes rejected", func(t *testing.T) {
+		t.Parallel()
+
+		_, err := parseOptionalMemoryBytes("-100")
+		require.Error(t, err)
+	})
+}
+
+func TestAppResourceLimitsRoundTrip(t *testing.T) {
+	t.Parallel()
+
+	// Test that parsing and formatting are consistent
+	tests := []struct {
+		input    string
+		expected sql.NullInt64
+		format   string
+	}{
+		{"256m", sql.NullInt64{Int64: 256 * 1024 * 1024, Valid: true}, "256m"},
+		{"1g", sql.NullInt64{Int64: 1024 * 1024 * 1024, Valid: true}, "1g"},
+		{"512k", sql.NullInt64{Int64: 512 * 1024, Valid: true}, "512k"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.input, func(t *testing.T) {
+			t.Parallel()
+
+			result, err := parseOptionalMemoryBytes(tt.input)
+			require.NoError(t, err)
+			assert.Equal(t, tt.expected, result)
+		})
+	}
+}