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

templates/app_edit.html

@@ -114,6 +114,38 @@
                 >
             </div>
 
+            <hr class="border-gray-200">
+
+            <h3 class="text-lg font-medium text-gray-900">Resource Limits</h3>
+
+            <div class="grid grid-cols-2 gap-4">
+                <div class="form-group">
+                    <label for="cpu_limit" class="label">CPU Limit (cores)</label>
+                    <input
+                        type="text"
+                        id="cpu_limit"
+                        name="cpu_limit"
+                        value="{{if .App.CPULimit.Valid}}{{.App.CPULimit.Float64}}{{end}}"
+                        class="input"
+                        placeholder="e.g. 0.5, 1, 2"
+                    >
+                    <p class="text-sm text-gray-500 mt-1">Number of CPU cores (e.g. 0.5 = half a core)</p>
+                </div>
+
+                <div class="form-group">
+                    <label for="memory_limit" class="label">Memory Limit</label>
+                    <input
+                        type="text"
+                        id="memory_limit"
+                        name="memory_limit"
+                        value="{{if .App.MemoryLimit.Valid}}{{formatMemoryBytes .App.MemoryLimit.Int64}}{{end}}"
+                        class="input"
+                        placeholder="e.g. 256m, 1g"
+                    >
+                    <p class="text-sm text-gray-500 mt-1">Memory with unit suffix (k, m, g) or plain bytes</p>
+                </div>
+            </div>
+
             <div class="flex justify-end gap-3 pt-4">
                 <a href="/apps/{{.App.ID}}" class="btn-secondary">Cancel</a>
                 <button type="submit" class="btn-primary">Save Changes</button>

templates/templates.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"html/template"
 	"io"
+	"strconv"
 	"sync"
 )
 
@@ -23,6 +24,34 @@ var (
 	templatesMutex sync.RWMutex
 )
 
+// templateFuncs returns the custom template function map.
+func templateFuncs() template.FuncMap {
+	return template.FuncMap{
+		"formatMemoryBytes": formatMemoryBytes,
+	}
+}
+
+// Memory unit constants.
+const (
+	memGigabyte = 1024 * 1024 * 1024
+	memMegabyte = 1024 * 1024
+	memKilobyte = 1024
+)
+
+// formatMemoryBytes formats bytes into a human-readable string with unit suffix.
+func formatMemoryBytes(bytes int64) string {
+	switch {
+	case bytes >= memGigabyte && bytes%memGigabyte == 0:
+		return strconv.FormatInt(bytes/memGigabyte, 10) + "g"
+	case bytes >= memMegabyte && bytes%memMegabyte == 0:
+		return strconv.FormatInt(bytes/memMegabyte, 10) + "m"
+	case bytes >= memKilobyte && bytes%memKilobyte == 0:
+		return strconv.FormatInt(bytes/memKilobyte, 10) + "k"
+	default:
+		return strconv.FormatInt(bytes, 10)
+	}
+}
+
 // initTemplates parses base template and creates cloned templates for each page.
 func initTemplates() {
 	templatesMutex.Lock()
@@ -32,8 +61,10 @@ func initTemplates() {
 		return
 	}
 
-	// Parse base template with shared components
-	baseTemplate = template.Must(template.ParseFS(templatesRaw, "base.html"))
+	// Parse base template with shared components and custom functions
+	baseTemplate = template.Must(
+		template.New("base.html").Funcs(templateFuncs()).ParseFS(templatesRaw, "base.html"),
+	)
 
 	// Pages that extend base
 	pages := []string{

templates/templates_test.go

@@ -0,0 +1,34 @@
+package templates //nolint:testpackage // tests unexported formatMemoryBytes
+
+import (
+	"testing"
+)
+
+func TestFormatMemoryBytes(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name     string
+		bytes    int64
+		expected string
+	}{
+		{"gigabytes", 1024 * 1024 * 1024, "1g"},
+		{"two gigabytes", 2 * 1024 * 1024 * 1024, "2g"},
+		{"megabytes", 256 * 1024 * 1024, "256m"},
+		{"kilobytes", 512 * 1024, "512k"},
+		{"plain bytes", 12345, "12345"},
+		{"non-even megabytes", 256*1024*1024 + 1, "268435457"},
+		{"zero", 0, "0"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			got := formatMemoryBytes(tt.bytes)
+			if got != tt.expected {
+				t.Errorf("formatMemoryBytes(%d) = %q, want %q", tt.bytes, got, tt.expected)
+			}
+		})
+	}
+}