chore: personalize Chirpy site (config, assets, demo posts

[khanhlove01]

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Improvement (refactoring and improving code)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update

Description

Summary of changes for this personal GitHub Pages site (Jekyll + Chirpy):

• Site identity: Updated _config.yml (title, social links, timezone, cleared theme CDN for local assets, url as applicable).
• About: Filled _tabs/about.md with a short bio and links.
• Branding: Local avatar under assets/img/avatar.jpg, sidebar object-position tweak in _sass/layout/_sidebar.scss, Poro favicon wired in _includes/favicons.html, site.webmanifest, and assets/feed.xml.
• Tooling / dev: .vscode/settings.json prepends Ruby and Node to PATH for Cursor on Windows; relaxed Ruby requirement in jekyll-theme-chirpy.gemspec for Ruby 4.x local use.
• CI / quality: Repointed demo post images to files under assets/img/sample/ and removed media_subpath where needed so HTML-Proofer no longer reports missing internal images.
• Deploy: GitHub Pages workflow and related config as already in the repo.

Motivation: Ship a usable personal blog with correct assets, passing checks, and conventional commits for CI (commitlint).

Dependencies: None beyond existing Ruby/Node/Jekyll toolchain; push includes binary assets (images).

Additional context

• Replaces earlier non-conventional commit messages by consolidating work in this branch with a proper chore: message.
• If anything still references old CDN-only paths, follow-up can trim or replace demo posts entirely.