[vo1dee]

What changed

• Added a Settings button to the main window toolbar, using SettingsLink.
• Added an Add Account… button to the sidebar. It opens the existing AccountForm in a sheet, so validation and Keychain handling stay in one place.
• The Accounts section in the sidebar now always shows, so the button is available with no accounts, for example after Configure Later in onboarding.
• Bumped the version to 1.1.0 (build 2) and added a changelog entry.

Closes #1
Closes #2

How it was tested

• swift test (57 tests)
• Tests/Integration/run.py, if SIP behaviour changed: not run, no SIP code changed
• Docs updated, including KNOWN_LIMITATIONS.md and CHANGELOG.md where relevant: CHANGELOG.md only, no limitations changed

Two new XCUITests pass in the real app: the Settings button brings the window forward without opening a second one, and the Add Account sheet opens and cancels with no accounts.

A temporary XCUITest also added extension 1006 from the sheet against the Asterisk rig. The sheet closed and the sidebar and Asterisk both showed it registered, without a relaunch. That test isn't included, because registering 1006 would interfere with run_app.py.

run_app.py was not run, so the incoming call UI test hasn't run against this change.