docs: fix CALENDSO_ENCRYPTION_KEY generation command (#26658)

The AES256 encryption used for 2FA requires exactly 32 bytes.
The previous command `openssl rand -base64 32` generates a 44-character
base64 string (32 bytes encoded in base64), which is too long.

Changed to `openssl rand -base64 24` which generates exactly 32
characters (24 bytes encoded in base64 = 32 characters).

This was causing 2FA setup failures with "Something went wrong" errors
and RangeError: Invalid key length in self-hosted Docker installations.

Fixes #22365

Co-authored-by: simiondolha <simiondolha@users.noreply.github.com>
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
Co-authored-by: Keith Williams <keithwillcode@gmail.com>

.env.example

@@ -94,7 +94,7 @@ CRON_ENABLE_APP_SYNC=false
 
 # Application Key for symmetric encryption and decryption
 # must be 32 bytes for AES256 encryption algorithm
-# You can use: `openssl rand -base64 24` to generate one
+# You can use: `openssl rand -base64 24` to generate a 32-character key
 CALENDSO_ENCRYPTION_KEY=
 
 # Intercom Config

agents/knowledge-base.md

@@ -13,7 +13,8 @@ Development
 - Install dependencies: `yarn`
 - Set up environment:
   - Copy `.env.example` to `.env`
-  - Generate keys with `openssl rand -base64 32` for both `NEXTAUTH_SECRET` and `CALENDSO_ENCRYPTION_KEY`
+  - Generate NEXTAUTH_SECRET with `openssl rand -base64 32`
+  - Generate CALENDSO_ENCRYPTION_KEY with `openssl rand -base64 24` (must be 32 characters for AES256)
   - Configure Postgres database URL in `.env`
   - Set DATABASE_DIRECT_URL to the same value as DATABASE_URL