Replace Sidekiq with Solid Queue for Active Job

[JuanVqz]

Summary

Switch Active Job from Sidekiq to Solid Queue, dropping the Redis dependency in favor of the Postgres-backed Solid Queue. Solid Queue already runs in-process in production via SOLID_QUEUE_IN_PUMA: true, so this makes it the actual adapter instead of running alongside an unused Sidekiq wiring.

Why

• The app declared both sidekiq/sidekiq-scheduler and solid_queue. The Active Job adapter was :sidekiq, yet deploy.yml does not provision Redis (commented out) while it does set SOLID_QUEUE_IN_PUMA: true. This consolidates on one backend.
• Removes Redis as an infrastructure requirement (Solid Queue uses the existing Postgres).
• Makes the open Sidekiq major-bump PRs (Bump sidekiq from 7.3.9 to 8.1.6 #84 sidekiq 8, Bump sidekiq-scheduler from 5.0.6 to 6.0.2 #87 sidekiq-scheduler 6) obsolete.

Changes

• config/application.rb: queue_adapter -> :solid_queue; add config.solid_queue.connects_to = { database: { writing: :queue } } (was missing entirely and is required for Solid Queue to use the queue database).
• config/recurring.yml: port the three cron schedules (daily puzzle, weekly leaderboard, inventory check) from sidekiq-scheduler.
• config/database.yml: add a queue database for development and test (production already defined one).
• Remove sidekiq + sidekiq-scheduler gems, config/initializers/sidekiq.rb, config/sidekiq.yml.
• Procfile: worker now runs bin/jobs.

Verification (local)

• Jobs enqueue into solid_queue_jobs with no Redis running.
• Recurring cron schedules parse as valid.
• Full test suite: 33 runs, 101 assertions, 0 failures, 0 errors.

Pending / for Operations

• Confirm production deploy provisions the queue Postgres database (ruby_or_rails_production_queue) and runs db:prepare.
• Decide whether to keep SOLID_QUEUE_IN_PUMA (single-server) or split a dedicated worker as traffic grows (already noted in deploy.yml).
• Remove any Redis accessory / REDIS_URL references from the deploy environment.

Draft until Operations confirms the production database/worker setup.