Fix #194: Allow --version/--help to run without TTY access

[Nihal-Pandey-2302]

Fixes #194

Problem: Running edit --version or edit --help failed in environments where /dev/tty was unavailable and stdin was not a TTY, because the application attempted to open /dev/tty during initial system setup.

Solution: This PR implements the approach suggested by @lhecker in the issue comments:

• Modified sys::init() to perform only minimal setup for default stdio handles (making sys::write_stdout() functional) without trying to open /dev/tty.
• Introduced a new sys::ensure_interactive_tty() function. This function now contains the logic to check if stdin is a TTY and, if necessary for interactive mode, opens /dev/tty and updates the relevant system state.
• Adjusted main.rs to:
  1. Call the modified sys::init().
  2. Check for --version or --help arguments. If present, print the info and exit (this path now bypasses the /dev/tty logic).
  3. If not an early exit, call sys::ensure_interactive_tty() before proceeding with full editor initialization.

This ensures that --version and --help can execute without needing full TTY access, while interactive mode still correctly sets up the TTY.

Testing Done:

• Verified that edit --version and edit --help with piped stdin (e.g., echo "test" | ./target/release/edit --version) now execute successfully and print the correct output.
• Confirmed that normal editor operations are unaffected:
  • edit (opens new file)
  • edit <filename> (opens existing file)
  • echo "content" | ./target/release/edit (correctly ingests piped content while allowing interactive TTY control). All local tests passed.

[Nihal-Pandey-2302]

@microsoft-github-policy-service agree

[lhecker]

We're not sure about the approach you've taken and will need longer to decide on whether to adopt this or not. I apologize for the wait.

[Nihal-Pandey-2302]

No worries

[Nihal-Pandey-2302]

Please inform me if the approach is fine or do I need to try something else?

[lhecker]

We should instead split up sys::init into two stages:

• Initialize the stdout/stdin handles (the call should never fail)
• Initialize all the rest and switch to raw mode (may fail)