Rebrand from MyCrib to Casera

- Update Go module from mycrib-api to casera-api
- Update all import statements across 69 Go files
- Update admin panel branding (title, sidebar, login form)
- Update email templates (subjects, bodies, signatures)
- Update PDF report generation branding
- Update Docker container names and network
- Update config defaults (database name, email sender, APNS topic)
- Update README and documentation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

internal/handlers/auth_handler.go

@@ -7,10 +7,10 @@ import (
 	"github.com/gin-gonic/gin"
 	"github.com/rs/zerolog/log"
 
-	"github.com/treytartt/mycrib-api/internal/dto/requests"
-	"github.com/treytartt/mycrib-api/internal/dto/responses"
-	"github.com/treytartt/mycrib-api/internal/middleware"
-	"github.com/treytartt/mycrib-api/internal/services"
+	"github.com/treytartt/casera-api/internal/dto/requests"
+	"github.com/treytartt/casera-api/internal/dto/responses"
+	"github.com/treytartt/casera-api/internal/middleware"
+	"github.com/treytartt/casera-api/internal/services"
 )
 
 // AuthHandler handles authentication endpoints