direnv integration for automatic environment activation #39

Summary

Include direnv in the dclaude image as a developer QoL enabler.

direnv automatically loads/unloads environment variables based on .envrc files when you cd into directories.

Use Cases

Project-specific environment variables:

# .envrc
export DATABASE_URL="postgres://localhost/myapp_dev"
export AWS_PROFILE="mycompany"

Nix environment auto-activation (complements #37):

# .envrc
use flake
# or: use nix

Tool version managers:

# .envrc
layout node
layout python

User Experience

$ dclaude exec bash
claude@container:~$ cd /path/to/project
direnv: loading .envrc
direnv: export +DATABASE_URL +AWS_PROFILE

claude@container:/path/to/project$ cd ..
direnv: unloading

Works identically on host (macOS/Linux) and in dclaude - same .envrc file.

Implementation

1. Install direnv in Dockerfile
2. Add direnv hook to .bashrc / .zshrc
3. Users create .envrc files in their projects

Relationship to Nix (#37)

direnv complements Nix integration:

Part of

#38 - Vision: dclaude as orchestrator, not tool provider