[feat] Add Docker development environment

- Add Dockerfile for Jekyll 4.2.0 with LiveReload
- Add docker-compose.yml with volume mounting for live file sync
- Include Gemfile and Gemfile.lock for dependency management

Author: ctr26

Dockerfile

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+FROM jekyll/jekyll:4.2.0
+
+WORKDIR /srv/jekyll
+
+COPY Gemfile* ./
+RUN bundle install
+
+COPY . .
+
+EXPOSE 4000
+
+CMD ["jekyll", "serve", "--host", "0.0.0.0", "--livereload"]

Gemfile

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+source "https://rubygems.org"
+
+gem "jekyll", "~> 4.2.0"
+gem "minima", "~> 2.5"
+
+group :jekyll_plugins do
+  gem "jekyll-feed", "~> 0.12"
+  gem "jekyll-seo-tag"
+end
+
+platforms :mingw, :x64_mingw, :mswin, :jruby do
+  gem "tzinfo", "~> 1.2"
+  gem "tzinfo-data"
+end
+
+gem "wdm", "~> 0.1.1", :platforms => [:mingw, :x64_mingw, :mswin]

Gemfile.lock

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+GEM
+  remote: https://rubygems.org/
+  specs:
+    addressable (2.8.0)
+      public_suffix (>= 2.0.2, < 5.0)
+    colorator (1.1.0)
+    concurrent-ruby (1.1.9)
+    em-websocket (0.5.2)
+      eventmachine (>= 0.12.9)
+      http_parser.rb (~> 0.6.0)
+    eventmachine (1.2.7)
+    ffi (1.15.3)
+    forwardable-extended (2.6.0)
+    http_parser.rb (0.6.0)
+    i18n (1.8.10)
+      concurrent-ruby (~> 1.0)
+    jekyll (4.2.0)
+      addressable (~> 2.4)
+      colorator (~> 1.0)
+      em-websocket (~> 0.5)
+      i18n (~> 1.0)
+      jekyll-sass-converter (~> 2.0)
+      jekyll-watch (~> 2.0)
+      kramdown (~> 2.3)
+      kramdown-parser-gfm (~> 1.0)
+      liquid (~> 4.0)
+      mercenary (~> 0.4.0)
+      pathutil (~> 0.9)
+      rouge (~> 3.0)
+      safe_yaml (~> 1.0)
+      terminal-table (~> 2.0)
+    jekyll-feed (0.15.1)
+      jekyll (>= 3.7, < 5.0)
+    jekyll-sass-converter (2.1.0)
+      sassc (> 2.0.1, < 3.0)
+    jekyll-seo-tag (2.7.1)
+      jekyll (>= 3.8, < 5.0)
+    jekyll-watch (2.2.1)
+      listen (~> 3.0)
+    kramdown (2.3.1)
+      rexml
+    kramdown-parser-gfm (1.1.0)
+      kramdown (~> 2.0)
+    liquid (4.0.3)
+    listen (3.5.1)
+      rb-fsevent (~> 0.10, >= 0.10.3)
+      rb-inotify (~> 0.9, >= 0.9.10)
+    mercenary (0.4.0)
+    minima (2.5.1)
+      jekyll (>= 3.5, < 5.0)
+      jekyll-feed (~> 0.9)
+      jekyll-seo-tag (~> 2.1)
+    pathutil (0.16.2)
+      forwardable-extended (~> 2.6)
+    public_suffix (4.0.6)
+    rb-fsevent (0.11.0)
+    rb-inotify (0.10.1)
+      ffi (~> 1.0)
+    rexml (3.2.3)
+    rouge (3.26.0)
+    safe_yaml (1.0.5)
+    sassc (2.4.0)
+      ffi (~> 1.9)
+    terminal-table (2.0.0)
+      unicode-display_width (~> 1.1, >= 1.1.1)
+    unicode-display_width (1.7.0)
+
+PLATFORMS
+  x86_64-linux-musl
+
+DEPENDENCIES
+  jekyll (~> 4.2.0)
+  jekyll-feed (~> 0.12)
+  jekyll-seo-tag
+  minima (~> 2.5)
+  tzinfo (~> 1.2)
+  tzinfo-data
+  wdm (~> 0.1.1)
+
+BUNDLED WITH
+   2.2.24

docker-compose.yml

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+version: '3.8'
+
+services:
+  jekyll:
+    image: jekyll/jekyll:4.2.0
+    container_name: jekyll-dev
+    ports:
+      - "4000:4000"
+      - "35729:35729"  # LiveReload port
+    volumes:
+      - .:/srv/jekyll
+    environment:
+      - JEKYLL_ENV=development
+    command: jekyll serve --host 0.0.0.0 --livereload --force_polling --incremental
+    stdin_open: true
+    tty: true