Added auto-generate secure passwords for Supabase template

[jorgepedro7]

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Título: feat(supabase): auto-generate secure passwords on install

Descrição:

## Problem
The current Supabase template ships with hardcoded insecure default passwords 
(`this_password_is_insecure_and_should_be_updated`, `your-super-secret-and-long-postgres-password`, etc.) 
that require manual intervention after every install.

## Solution
- Added `postgresPassword`, `dashboardPassword` and `jwtSecret` fields with `generatePassword: true`
- All other secrets (SECRET_KEY_BASE, VAULT_ENC_KEY, PG_META_CRYPTO_KEY, LOGFLARE tokens, POOLER_TENANT_ID) are also auto-generated
- Updated instructions to reflect the new behavior

## Testing
Tested on a self-hosted VPS with Easypanel running the full Supabase stack.

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[Ahson-Shaikh]

Hi - @jorgepedro7. We have faced issues while deploying the Supabase template using the above suggested method. I'm closing this now, and keeping this in backlog to test it later on.