feat: Add multi-repo support

[rhoades-brown]

Summary

Adds support for syncing multiple GitHub repositories to specific vault directories, each with independent sync state and configuration.

Changes

New Features

• Additional repositories settings section — Add, remove, and configure extra repos from the settings tab
• Per-repo sync — Each additional repo gets its own GitHubService and SyncService instance
• Path overlap validation — Prevents configuring repos with overlapping vault directories
• Independent auth — Each repo can use the main token or a separate PAT
• SyncView integration — Additional repo changes appear in the sync view with repo badges
• Main repo exclusion — Automatically excludes additional repo directories from main repo sync

Files Changed

• main.ts — AdditionalRepoRuntime interface, initializeAdditionalRepos(), syncAdditionalRepos(), getMainRepoIgnorePatterns()
• src/types/settings.ts — AdditionalRepoConfig interface, added \�dditionalRepos\ to settings
• src/services/syncService.ts — \localBasePath\ support, \ oRelativeLocalPath(), \ oAbsoluteLocalPath()\
• src/ui/settingsTab.ts — Additional repos settings UI section
• src/views/SyncView.ts — Multi-repo change aggregation with repo labels
• styles.css — Additional repo card and badge styles
• ** ests/services/syncService.test.ts** — 21 new tests for path validation, ignore patterns, and path conversion

Verification

• ✅ Build passes
• ✅ All 119 tests pass (98 existing + 21 new)
• ✅ Lint passes with zero errors