Set up Rails 8 application foundation

- Generate Rails 8.1 app with PostgreSQL and TailwindCSS
- Add docker-compose.yml (postgres:17) for local database
- Configure database.yml to connect to Dockerized Postgres via env vars
- Add Pages#home root route, application layout, and navbar partial

config/initializers/content_security_policy.rb

@@ -0,0 +1,29 @@
+# Be sure to restart your server when you modify this file.
+
+# Define an application-wide content security policy.
+# See the Securing Rails Applications Guide for more information:
+# https://guides.rubyonrails.org/security.html#content-security-policy-header
+
+# Rails.application.configure do
+#   config.content_security_policy do |policy|
+#     policy.default_src :self, :https
+#     policy.font_src    :self, :https, :data
+#     policy.img_src     :self, :https, :data
+#     policy.object_src  :none
+#     policy.script_src  :self, :https
+#     policy.style_src   :self, :https
+#     # Specify URI for violation reports
+#     # policy.report_uri "/csp-violation-report-endpoint"
+#   end
+#
+#   # Generate session nonces for permitted importmap, inline scripts, and inline styles.
+#   config.content_security_policy_nonce_generator = ->(request) { request.session.id.to_s }
+#   config.content_security_policy_nonce_directives = %w(script-src style-src)
+#
+#   # Automatically add `nonce` to `javascript_tag`, `javascript_include_tag`, and `stylesheet_link_tag`
+#   # if the corresponding directives are specified in `content_security_policy_nonce_directives`.
+#   # config.content_security_policy_nonce_auto = true
+#
+#   # Report violations without enforcing the policy.
+#   # config.content_security_policy_report_only = true
+# end