fix: OPDS base_url placeholder bug + setup gate requires base_url

Three bugs fixed:

1. Schema seeded base_url with fake placeholder 'bookhoard.example.com'.
   Removed seed; startup now seeds from BASE_URL env var only if DB row
   is empty (admin changes persist across restarts). One-time UPDATE
   clears the placeholder in existing installs.

2. config.GetBaseURL() had a broken type assertion (local SystemConfigRow
   vs database.SystemConfig) that always failed, returning . Admin panel
   showed env var fallback instead of actual DB value. Fixed with a
   function-type getter that properly wraps the DB query.

3. OPDS handler read base_url only from DB with no fallback. When DB had
   the placeholder, all feed links pointed to an unreachable domain,
   breaking KOReader search/download. Added deriveBaseURL() helper that
   falls back to the request Host/scheme when DB value is empty.

Setup gate improvements:
- isSetupComplete now requires both admin user AND non-empty base_url
- Setup middleware no longer exempts all /api/ routes; only allows
  /api/auth/register, /api/auth/login, /api/system/config before setup
  is complete. All other API routes get 503.
- Cache invalidated when base_url is saved via admin settings

Dev workflow:
- New bruno/NewDevDBSetup/SetBaseUrl.yml for dev DB setup
- NewDB.sh runs SetBaseUrl between RegisterUser and CreateEbookLibrary

internal/router/frontend.go

@@ -9,7 +9,6 @@ import (
 	"strconv"
 	"time"
 
-	"bookhoard/internal/config"
 	"bookhoard/internal/database"
 	"bookhoard/internal/handlers"
 	"bookhoard/internal/services"
@@ -734,10 +733,7 @@ func registerFrontendRoutes(cfg *Config) {
 		}
 
 		// Get base URL from database config with fallback to config/env var
-		baseURL := config.GetBaseURL(c.Request().Context(), cfg.Queries)
-		if baseURL == "" {
-			baseURL = cfg.Cfg.BaseURL
-		}
+		baseURL := cfg.getBaseURL(c.Request().Context())
 
 		var buf bytes.Buffer
 		err = templates.Devices(user, devices, pendingList, errorMsg, baseURL).Render(c.Request().Context(), &buf)
@@ -995,10 +991,7 @@ func registerFrontendRoutes(cfg *Config) {
 		}
 
 		// Fetch current system configuration - just base_url
-		baseURL := config.GetBaseURL(c.Request().Context(), cfg.Queries)
-		if baseURL == "" {
-			baseURL = cfg.Cfg.BaseURL
-		}
+		baseURL := cfg.getBaseURL(c.Request().Context())
 
 		systemConfig := map[string]string{
 			"base_url":         baseURL,
@@ -1086,10 +1079,7 @@ func registerFrontendRoutes(cfg *Config) {
 		}
 
 		// Get base URL from database config with fallback to config/env var
-		baseURL := config.GetBaseURL(c.Request().Context(), cfg.Queries)
-		if baseURL == "" {
-			baseURL = cfg.Cfg.BaseURL
-		}
+		baseURL := cfg.getBaseURL(c.Request().Context())
 
 		var buf bytes.Buffer
 		err = templates.Devices(user, devices, pendingList, errorMsg, baseURL).Render(c.Request().Context(), &buf)

internal/router/router.go

@@ -72,6 +72,24 @@ type Config struct {
 	LibraryService          *services.LibraryService
 }
 
+// getBaseURL returns the configured base URL from the database, falling back to
+// the env var / config default. Uses a closure to adapt the database query to
+// config.SystemConfigGetter.
+func (cfg *Config) getBaseURL(ctx context.Context) string {
+	getter := func(ctx context.Context, key string) (string, error) {
+		row, err := cfg.Queries.GetSystemConfig(ctx, key)
+		if err != nil {
+			return "", err
+		}
+		return row.Value, nil
+	}
+	baseURL := config.GetBaseURL(ctx, getter)
+	if baseURL == "" {
+		baseURL = cfg.Cfg.BaseURL
+	}
+	return baseURL
+}
+
 // createJWTMiddleware creates a JWT middleware with proper user context setup
 func createJWTMiddleware(cfg *Config) echo.MiddlewareFunc {
 	return echojwt.WithConfig(echojwt.Config{

internal/router/setup.go

@@ -14,7 +14,40 @@ import (
 )
 
 func isSetupComplete(cfg *Config) bool {
-	return setupstatus.IsSetupComplete(context.Background(), cfg.Queries)
+	getter := func(ctx context.Context) (string, error) {
+		row, err := cfg.Queries.GetSystemConfig(ctx, "base_url")
+		if err != nil {
+			return "", err
+		}
+		return row.Value, nil
+	}
+	return setupstatus.IsSetupComplete(context.Background(), cfg.Queries, getter)
+}
+
+// setupAllowedAPIRoutes lists API endpoints that remain accessible before
+// initial setup is complete so the server can be configured via API.
+var setupAllowedAPIRoutes = []string{
+	"/api/auth/register",
+	"/api/auth/login",
+	"/api/system/config",
+}
+
+// isAllowedDuringSetup reports whether a request path should bypass the setup
+// gate. This includes the setup page itself, static assets, health checks, and
+// the minimal set of API routes needed to perform initial configuration.
+func isAllowedDuringSetup(path string) bool {
+	if path == "/setup" || path == "/setup/" {
+		return true
+	}
+	if strings.HasPrefix(path, "/static/") || path == "/health" || path == "/favicon.ico" {
+		return true
+	}
+	for _, route := range setupAllowedAPIRoutes {
+		if path == route || strings.HasPrefix(path, route+"/") {
+			return true
+		}
+	}
+	return false
 }
 
 func setupRedirectMiddleware(cfg *Config) echo.MiddlewareFunc {
@@ -22,19 +55,16 @@ func setupRedirectMiddleware(cfg *Config) echo.MiddlewareFunc {
 		return func(c *echo.Context) error {
 			path := c.Request().URL.Path
 
-			if path == "/setup" || path == "/setup/" {
-				return next(c)
-			}
-
-			if strings.HasPrefix(path, "/api/") {
-				return next(c)
-			}
-
-			if strings.HasPrefix(path, "/static/") || path == "/health" || path == "/favicon.ico" {
+			if isAllowedDuringSetup(path) {
 				return next(c)
 			}
 
 			if !isSetupComplete(cfg) {
+				if strings.HasPrefix(path, "/api/") {
+					return c.JSON(http.StatusServiceUnavailable, map[string]string{
+						"error": "Server setup is not complete. Configure an admin account and base_url via the setup wizard or API.",
+					})
+				}
 				return c.Redirect(http.StatusFound, "/setup")
 			}