Remove config/tenant/showcases.yml from git tracking

Showcases configuration is now generated from db/index.sqlite3 into
db/showcases.yml, with db/deployed-showcases.yml tracking deployed state
for change detection. This eliminates the need for git commits when
admins create or modify showcases.

Also removes obsolete Passenger/nginx deployment files that are no longer
used since both Fly.io and Kamal deployments now use Navigator.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: rubys

README.md

@@ -51,12 +51,13 @@ cd Showcase
 bundle install
 rm config/credentials.yml.enc
 bin/rails credentials:edit
-$EDITOR config/tenant/showcases.yml
 docker compose build
 docker compose up
 docker compose exec web bin/bootstrap
 ```
 
+Note: Showcase configuration is managed via the admin interface at `/admin`, which stores data in `db/index.sqlite3` and generates `db/showcases.yml` automatically.
+
 Visit http://localhost:9999/showcase/ to see the list of events.
 
 # Implementation overview

app/controllers/admin_controller.rb

@@ -31,7 +31,7 @@ def index
       return
     end
 
-    showcases = YAML.load_file('config/tenant/showcases.yml')
+    showcases = ShowcasesLoader.load
 
     cities = Set.new
     @events = 0
@@ -166,11 +166,7 @@ def apply
       @move[site] = {from: was[:region], to: info[:region]}
     end
 
-    # Determine which file to use for previous state
-    previous_file = File.exist?('db/deployed-showcases.yml') ?
-      'db/deployed-showcases.yml' : 'config/tenant/showcases.yml'
-
-    previous = parse_showcases(previous_file)
+    previous = parse_showcases('db/deployed-showcases.yml')
     showcases = parse_showcases('db/showcases.yml')
     @showcases_modified = showcases - previous
     @showcases_removed = previous - showcases - @showcases_modified

bin/apply-changes.rb

@@ -74,10 +74,6 @@
   if !File.exist?(deployed_file) || new_showcases != IO.read(deployed_file)
     IO.write(deployed_file, new_showcases)
   end
-  # Also update git-tracked file for now (will be removed in Phase 3)
-  if new_showcases != IO.read('config/tenant/showcases.yml')
-    IO.write('config/tenant/showcases.yml', new_showcases)
-  end
 end
 
 # deploy changes