hotfix: plugin manager infinite loading

- frontend: RPC timeout (8s), try/catch/finally on reload, proper UI
  states (loading/error/empty/list)
- frontend: reload() now sets loading=true, catches errors
- backend: tilde expansion (~/.config/verstak/plugins → /home/mirivlad/...)
- backend: ReloadPlugins returns diagnostics (count, summary string)
- backend: diagnostic logging in DiscoverPlugins (start/dirs/entries/results)
- backend: FormatDiscoverySummary helper
- testing: 11 headless tests for DiscoverPlugins (empty, missing, valid,
  broken JSON, duplicate ID, multiple dirs, nonexistent mix)

internal/api/app.go

@@ -2,6 +2,11 @@
 package api
 
 import (
+	"log"
+	"os"
+	"path/filepath"
+	"strings"
+
 	"github.com/verstak/verstak-desktop/internal/core/capability"
 	"github.com/verstak/verstak-desktop/internal/core/contribution"
 	"github.com/verstak/verstak-desktop/internal/core/events"
@@ -37,6 +42,7 @@ func NewApp(
 
 // Startup is called when the app starts.
 func (a *App) Startup() error {
+	log.Printf("[api] App.Startup: initialized with %d plugins", len(a.plugins))
 	return nil
 }
 
@@ -44,17 +50,22 @@ func (a *App) Startup() error {
 
 // GetPlugins returns all discovered plugins.
 func (a *App) GetPlugins() []plugin.Plugin {
+	log.Printf("[api] GetPlugins: returning %d plugins", len(a.plugins))
 	return a.plugins
 }
 
 // GetCapabilities returns all registered capabilities.
 func (a *App) GetCapabilities() []capability.Entry {
-	return a.capRegistry.List()
+	entries := a.capRegistry.List()
+	log.Printf("[api] GetCapabilities: returning %d entries", len(entries))
+	return entries
 }
 
 // GetPermissions returns all known permissions.
 func (a *App) GetPermissions() []permissions.Entry {
-	return a.permRegistry.List()
+	entries := a.permRegistry.List()
+	log.Printf("[api] GetPermissions: returning %d entries", len(entries))
+	return entries
 }
 
 // GetContributions returns all registered contributions.
@@ -70,14 +81,58 @@ func (a *App) GetContributions() ContributionSummary {
 	}
 }
 
-// ReloadPlugins re-discovers plugins from disk.
-func (a *App) ReloadPlugins() {
+// expandPath resolves "~" to the user's home directory.
+func expandPath(path string) string {
+	if strings.HasPrefix(path, "~/") {
+		home, err := os.UserHomeDir()
+		if err != nil {
+			log.Printf("[api] expandPath: cannot get home dir: %v", err)
+			return path
+		}
+		return filepath.Join(home, path[2:])
+	}
+	return path
+}
+
+// ReloadPlugins re-discovers plugins from disk and returns a summary.
+func (a *App) ReloadPlugins() (int, string) {
 	discoveryDirs := []string{
 		"~/.config/verstak/plugins",
 		"./plugins",
 	}
-	plugins, _ := plugin.DiscoverPlugins(discoveryDirs)
+
+	// Expand tilde in all paths
+	for i, d := range discoveryDirs {
+		discoveryDirs[i] = expandPath(d)
+	}
+
+	log.Printf("[api] ReloadPlugins: scanning dirs: %v", discoveryDirs)
+
+	plugins, errs := plugin.DiscoverPlugins(discoveryDirs)
 	a.plugins = plugins
+
+	var buf strings.Builder
+	buf.WriteString("discovery complete")
+	if len(plugins) > 0 {
+		buf.WriteString(": ")
+		buf.WriteString(plugin.FormatDiscoverySummary(plugins))
+	}
+
+	if len(errs) > 0 {
+		log.Printf("[api] ReloadPlugins: %d warning(s)", len(errs))
+		for _, e := range errs {
+			log.Printf("[api]   discovery warning: %v", e)
+		}
+	}
+
+	log.Printf("[api] ReloadPlugins: discovered %d plugin(s)", len(plugins))
+
+	discoveryDirsStr := strings.Join(discoveryDirs, ", ")
+	summary := buf.String()
+
+	log.Printf("[api] ReloadPlugins: dirs=[%s] %s", discoveryDirsStr, summary)
+
+	return len(plugins), summary
 }
 
 // ContributionSummary aggregates all contribution types for the frontend.