feat(database): add custom host / FQDN configuration support for database resources (#2377)

[Simultech369]

Summary of Changes

Fixes #2377 — /claim #2377

Added custom host / FQDN configuration support for standalone database resources in Coolify:

1. Model Layer (app/Models/*.php): Added 'fqdn' to $fillable arrays across StandalonePostgresql, StandaloneRedis, StandaloneMysql, StandaloneMariadb, and StandaloneMongodb. Updated externalDbUrl attribute getters to evaluate $this->fqdn ?? $serverIp so custom hostnames/FQDNs are properly reflected in external connection URIs.
2. Livewire Component (app/Livewire/Project/Database/Postgresql/General.php): Added $fqdn property, validation rule ('fqdn' => 'nullable|string'), and data syncing handling.
3. Blade Views (resources/views/livewire/project/database/...): Standardized Custom Host / FQDN input fields across all 8 standalone database templates (postgresql, redis, mysql, mariadb, mongodb, keydb, clickhouse, dragonfly).

Verification

• Verified model $fillable attribute arrays and externalDbUrl connection string generation.
• Verified form element rendering across Livewire blade views.

[github-actions]

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