feat: migrate settings UI to declarative API

[rhoades-brown]

Summary

Migrates the settings tab from the imperative display() method to the new declarative Settings API introduced in Obsidian 1.13.0, and adds additional 1.13.0 API enhancements.

Declarative Settings Migration

• Replaced display() with getSettingDefinitions() returning an array of declarative definitions
• Added getControlValue / setControlValue with dot-notation support for nested settings objects
• Auth section uses render callbacks for connection status and Connect button
• Repository section uses dynamic dropdown via render callback
• Additional repos use type: 'list' with page navigation
• Ignore patterns use type: 'list' with inline editing
• Sync behavior uses visible predicates (interval slider only shown when enabled)
• Commit, conflict, UI sections use pure declarative control bindings
• Logging uses render callbacks for side-effects (logger.configure())
• All this.display() calls replaced with this.update()
• All eslint-disable comments removed

1.13.0 API Enhancements

• ConfirmationModal: Replaced placeholder SyncModal with reusable confirmDestructiveAction helper using native ConfirmationModal API for delete repo and clear logs confirmations
• setDestructive: Applied destructive styling to Clear logs buttons in both Settings Tab and SyncView
• setErrorMessage: Inline validation errors for PAT connection failures and vault directory path overlaps, replacing Notice-based alerts
• Plugin.settings: Fixed setControlValue to use saveSettings() instead of saveData() to preserve sync state

Breaking Change

• minAppVersion bumped from 1.7.2 to 1.13.0

Checklist

• Build passes
• Lint clean (0 errors/warnings)
• All 119 tests pass
• Mock updated with 1.13.0 API types

Draft: This PR should remain in draft until Obsidian 1.13.0 is publicly released.