feat(chrome-ext): add site preferences checklist to options page

[draphy]

Issues

Fixes #4067

Description

Adds a "Site Preferences" section to the options page so users can see and manage every site with an explicit Harper setting. Bundled default sites get a searchable checklist with bulk enable/disable and per-site toggles; custom sites with explicit settings are listed and can be reset. Domain keys are normalized to www. -stripped hostnames so legacy www. keys can never shadow newer overrides.

Demo

How Has This Been Tested?

E2E test covering bulk default toggling, custom site management, and lint gating; passes on Chromium.

AI Disclosure

• I am a human and didn't use any AI.
• I used LLM features of my editor, but not an agent.
• I consulted one or more coding AIs, but didn't use an agent.
• I used an AI agent interactively.
• I am an agent or I got an agent to do the work autonomously.

Checklist

• I have performed a self-review of my own code
• I have added tests to cover my changes
• I have considered splitting this into smaller pull requests.