fix: columna FK incorrecta en contrato_servidores y filtrado de BDs en modal

- syncContratoJoin derivaba "contrato_servidore_id" en vez de "servidor_id"
  al recortar el último carácter del nombre de tabla; ahora usa TrimPrefix+TrimSuffix
  para derivar correctamente servidor_id, conx_db_id, ai_config_id
- Modal contratos: filteredConxDbList filtra BDs por servidor(es) seleccionado(s)
  en vez de mostrar todas las BDs sin contexto

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

pkg/models/contrato.go

@@ -2,6 +2,7 @@ package models
 
 import (
 	"log"
+	"strings"
 	"time"
 
 	"github.com/sujit-baniya/fiber-boilerplate/app"
@@ -155,8 +156,11 @@ func syncContratoJoin(db *gorm.DB, table string, contratoID uint, ids []uint) er
 	if err := db.Exec("DELETE FROM "+table+" WHERE contrato_id = ?", contratoID).Error; err != nil {
 		return err
 	}
+	// Derive FK column: "contrato_servidores" → "servidor_id", "contrato_conx_dbs" → "conx_db_id"
+	entityPlural := strings.TrimPrefix(table, "contrato_")
+	fkCol := strings.TrimSuffix(entityPlural, "s") + "_id"
 	for _, id := range ids {
-		if err := db.Exec("INSERT INTO "+table+" (contrato_id, "+table[:len(table)-1]+"_id) VALUES (?, ?) ON CONFLICT DO NOTHING",
+		if err := db.Exec("INSERT INTO "+table+" (contrato_id, "+fkCol+") VALUES (?, ?) ON CONFLICT DO NOTHING",
 			contratoID, id,
 		).Error; err != nil {
 			return err

resources/views/renovaciones/contratos.html

@@ -230,7 +230,7 @@
                     <div class="col-span-2">
                         <label class="text-xs font-medium text-gray-600 mb-1 block">Bases de datos <span class="font-normal text-gray-400">(filtradas por servidor seleccionado)</span></label>
                         <div class="border rounded max-h-32 overflow-y-auto divide-y text-sm">
-                            <template x-for="db in conxDbList" :key="db.ID">
+                            <template x-for="db in filteredConxDbList" :key="db.ID">
                                 <label class="flex items-center gap-2 px-3 py-1.5 hover:bg-gray-50 cursor-pointer">
                                     <input type="checkbox" :value="db.ID"
                                         :checked="form.conx_db_ids.includes(db.ID)"
@@ -238,7 +238,7 @@
                                     <span x-text="db.nombre"></span>
                                 </label>
                             </template>
-                            <div x-show="conxDbList.length===0" class="text-xs text-gray-400 px-3 py-2">
+                            <div x-show="filteredConxDbList.length===0" class="text-xs text-gray-400 px-3 py-2">
                                 <span x-text="form.servidor_ids.length > 0 ? 'Sin BD para los servidores seleccionados' : 'Selecciona un servidor primero'"></span>
                             </div>
                         </div>
@@ -476,6 +476,11 @@ document.addEventListener('alpine:init', () => {
             if (idx === -1) { this.form.ai_config_ids.push(id); } else { this.form.ai_config_ids.splice(idx, 1); }
         },
 
+        get filteredConxDbList() {
+            if (!this.form.servidor_ids || this.form.servidor_ids.length === 0) return [];
+            return this.conxDbList.filter(db => this.form.servidor_ids.includes(db.servidor_id));
+        },
+
         get precioSugerido() {
             return this.servicios
                 .filter(s => (this.form.servicio_ids || []).includes(s.ID))