feat: edit .factoryfloor.json from the GUI

[davidpoblador]

Context

Requested by @Hormold in #338 (comment): #338 (comment)

Problem

Users would like to edit project configuration (.factoryfloor.json) directly from the app instead of manually editing the file.

Challenge

.factoryfloor.json lives in the repo, so GUI edits raise questions:

• Commit & push? That affects all worktrees and collaborators.
• Local override only? Then the GUI state diverges from what's checked in, which can be confusing.
• Per-worktree overrides? Adds complexity and potential for config drift.

We need to figure out a UX that makes this intuitive without creating surprising side effects.

Ideas to explore

• Read-only view of the current config in the Environment tab (Cmd+E), with an "Open in editor" button as a first step
• A local .factoryfloor.local.json override mechanism (not checked in)
• GUI editing that stages changes but lets the user decide when to commit

Related

• docs: improve discoverability of setup scripts, run scripts, and environment features #338 — docs: improve discoverability of setup scripts, run scripts, and environment features

[davidpoblador]

@Hormold FYI — tagging you here so you get notifications on this one.