feat: add function to append values to existing multiline or single-line lists while preserving formatting

[Scott McMaster (scottmcmaster)]

Summary

Removes the TODO in edit_nix_file about preserving list commenting and formatting.

Test Plan

Added/updated unit tests. Also manual testing, for example see the screenshot.

Docs

• Docs updated
• No docs update needed

[github-actions]

	Warnings
⚠️	Please assign this PR to someone (usually yourself).

	Messages
📖	No docs update needed — acknowledged.

📋 PR Overview

Lines changed	199 (+183 / -16)
Files	0 added, 1 modified, 0 deleted
Draft / WIP	no
Has Test Plan	yes
New UI components	no
New Storybook stories	no
New Rust modules	no
New TS source files	no
New tests	no
package.json touched	no
Cargo.toml touched	no
Infra / CI touched	no

🔬 Coverage

Report	Lines	Statements	Functions	Branches
apps/native/coverage/coverage-summary.json	17.3%	17.3%	27.8%	52.9%

Generated by 🚫 dangerJS against 8ffdb9b

[Copilot]

Pull request overview

This PR improves Nix list editing in the Tauri native “evolve” layer by appending new list items into an existing list literal without rewriting the whole list, preserving existing multiline formatting and comment structure (removing the prior TODO about formatting loss).

Changes:

• Added append_values_to_existing_list() to insert new values before the list’s closing bracket while preserving formatting.
• Updated add() to append only missing values to an existing list rather than replacing the full list text.
• Expanded/updated unit tests to validate formatting preservation for commented and multiline lists.

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