run_bash: optionally wrap in direnv exec for dev shell env

Wrap run_bash commands in direnv exec to get full dev shell environment.

Problem

Ava's run_bash only has explicitly declared rundeps in PATH. Many tools from the dev shell (nix develop) aren't available.

Solution

Modify executeRunBash in Tools.hs to optionally wrap commands:

-- If CODEROOT has a .envrc, wrap in direnv exec
let wrappedCmd = 
  if hasDirenv coderoot
  then "direnv exec " <> coderoot <> " bash -c " <> shellQuote cmd
  else cmd

Requirements

1. Add direnv as a rundep to Ava 2. Detect if working directory has .envrc 3. Shell-quote the command properly 4. Consider cwd parameter - may need different .envrc

Alternative

Just keep adding explicit rundeps as needed. Simpler but more manual.