fix: enable Option+Backspace word deletion in terminal

[AndresGonzalez5]

Summary

• Option+Backspace (delete word) doesn't work in Factory Floor's embedded terminal — it produces a composed special character instead of sending ESC+DEL
• Configures Ghostty's macos-option-as-alt = left so the left Option key acts as Alt/Meta
• Right Option remains the macOS compose key for accented characters (ñ, ü, etc.)
• Adds proper modifier translation in keyDown using Ghostty's ghostty_surface_key_translation_mods API, so interpretKeyEvents sees the base character
• Adds sided modifier detection (NX_DEVICE* masks) to distinguish left vs right Option

Changes

• TerminalApp.swift: Loads macos-option-as-alt = left config into Ghostty at init
• TerminalView.swift: Translates modifier flags before interpretKeyEvents using Ghostty's translation API; adds sided modifier detection and ghosttyModsToFlags reverse helper

Test plan

• Open a terminal tab and press Option+Backspace — should delete the previous word
• Press Option+Left/Right arrow — should jump word-by-word
• Press Right Option+e, then a — should produce á (compose key still works)
• Press Right Option+n, then n — should produce ñ
• Verify IME / dead key input (e.g., Japanese, Korean) still works correctly

🤖 Generated with Claude Code

[AndresGonzalez5]

I always use left option instead of the one on the right, so I put = left, but feel free to modify it. I found the improvement useful :)

[davidpoblador]

Thanks for the PR! A couple of questions before we move forward:

1. Do you have Ghostty installed on your machine? Factory Floor's embedded terminals inherit your Ghostty config from ~/.config/ghostty/config. If you have macos-option-as-alt set there, it would already apply inside Factory Floor.

2. Does Option+Backspace work for you in standalone Ghostty (or whichever terminal emulator you normally use)? Ghostty has a keyboard layout heuristic that auto-enables option-as-alt on US/US International layouts even without explicit config. If you're on a non-US layout, the default is off — which would explain the issue.

3. What keyboard layout are you using? (US, Spanish, etc.)

Asking because this determines the right fix. One concern with the current approach: ghostty_config_load_file is called after ghostty_config_load_default_files, so it would override whatever the user has in their own Ghostty config for this setting. For example, someone with macos-option-as-alt = true would get silently downgraded to left.

[AndresGonzalez5]

No problem! I've been playing with the project a bit to fit the specific AI workflow I already had with worktrees.

1. I do have Ghostty and use it heavily. The only config besides keybindings and theme modification is the macos-option-as-alt. Once I started using FactoryFloor I noticed that it stopped working, so something must have overriden my configuration (hence the PR)
2. Yes, it works in standalone terminal because I added that config line in my Ghostty settings
3. I use a MacBook from the US, with the keyboard set to International US (to be able to write tildes in Spanish)

I also had to jump through some hoops in order to build the xcFramework in macOS Tahoe, if it makes any difference.