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/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{