Initialize direnv in bling.sh

[zktaiga]

Description

Initialize direnv in bling.sh for bash and zsh. direnv is already shipped in bluefin-cli.Brewfile but was non-functional without shell initialization.

direnv by default has built-in safeguards, so you'll still need to run direnv allow wherever necessary.

A small note: direnv is initialized before bash-preexec to avoid PROMPT_COMMAND conflicts. There's an edge case in bash-preexec where if direnv modifies PROMPT_COMMAND after bash-preexec sources, it breaks atuin's history capture. By initializing direnv first, we avoid this issue entirely. See:

• Re-adjust PROMPT_COMMAND when PROMPT_COMMAND is modified elsewhere rcaloras/bash-preexec#143

Type of Change

• Bug fix/new feature (direnv was installed but not configured OOTB)

Testing Done

• Tested on running system: Yes (manually sourced modified bling.sh, verified direnv and atuin both work)