Remove payment/subscription system and card/storage limits

Fizzy is now free. Remove the entire Stripe billing system,
subscription management, and card/storage limit enforcement.

Removes from saas/: Plan model, Account::Billing, Account::Subscription,
Account::Limited, Account::OverriddenLimits, Account::BillingWaiver,
all subscription/billing controllers and views, Stripe webhook handler,
card creation/publishing limit enforcement, admin account override UI,
usage report rake task, and all related tests.

Removes from main app: Fizzy.saas? guards for subscription panel,
SaaS card footer override, near-limit notices, and saas.css stylesheet.

Adds migration to drop billing tables from the SaaS database.

Non-billing SaaS features (push notifications, signup, authorization,
telemetry, console1984/audits1984) are preserved.

saas/exe/stripe-dev

@@ -1,83 +0,0 @@
-#!/usr/bin/env ruby
-#
-# Fetches Stripe development environment variables from 1Password and starts
-# the Stripe CLI webhook listener.
-#
-# Usage: eval "$(bundle exec stripe-dev)"
-
-require "json"
-require "fileutils"
-
-LOG_FILE = "log/stripe.development.log"
-PID_FILE = "tmp/stripe.tunnel.pid"
-
-# Ensure directories exist
-FileUtils.mkdir_p("log")
-FileUtils.mkdir_p("tmp")
-
-# Kill any existing stripe tunnel process
-if File.exist?(PID_FILE)
-  old_pid = File.read(PID_FILE).strip.to_i
-  if old_pid > 0
-    Process.kill("TERM", old_pid) rescue nil
-  end
-  File.delete(PID_FILE)
-end
-
-# Fetch secrets from 1Password
-secrets_escaped = `kamal secrets fetch \
-  --adapter 1password \
-  --account 23QPQDKZC5BKBIIG7UGT5GR5RM \
-  --from "Deploy/Fizzy" \
-  "Development/STRIPE_SECRET_KEY" \
-  "Development/STRIPE_MONTHLY_V1_PRICE_ID" \
-  "Development/STRIPE_MONTHLY_EXTRA_STORAGE_V1_PRICE_ID" 2>/dev/null`
-
-secrets_json = secrets_escaped.gsub(/\\(.)/, '\1')
-secrets = JSON.parse(secrets_json)
-
-stripe_secret_key = secrets["Deploy/Fizzy/Development/STRIPE_SECRET_KEY"]
-stripe_price_id = secrets["Deploy/Fizzy/Development/STRIPE_MONTHLY_V1_PRICE_ID"]
-stripe_extra_storage_price_id = secrets["Deploy/Fizzy/Development/STRIPE_MONTHLY_EXTRA_STORAGE_V1_PRICE_ID"]
-
-# Clear previous log file
-File.write(LOG_FILE, "")
-
-# Start stripe listen in background
-pid = spawn(
-  "stripe", "listen", "--forward-to", "localhost:3006/stripe/webhooks",
-  out: [ LOG_FILE, "a" ],
-  err: [ LOG_FILE, "a" ]
-)
-Process.detach(pid)
-
-# Save PID for cleanup
-File.write(PID_FILE, pid.to_s)
-
-# Wait for the webhook secret to appear in logs
-webhook_secret = nil
-20.times do
-  sleep 0.5
-  if File.exist?(LOG_FILE)
-    content = File.read(LOG_FILE)
-    if match = content.match(/webhook signing secret is (whsec_\w+)/)
-      webhook_secret = match[1]
-      break
-    end
-  end
-end
-
-if webhook_secret.nil?
-  warn "Warning: Could not capture webhook secret from stripe listen"
-end
-
-# Output export statements
-puts %Q(export STRIPE_SECRET_KEY="#{stripe_secret_key}")
-puts %Q(export STRIPE_MONTHLY_V1_PRICE_ID="#{stripe_price_id}")
-puts %Q(export STRIPE_MONTHLY_EXTRA_STORAGE_V1_PRICE_ID="#{stripe_extra_storage_price_id}")
-puts %Q(export STRIPE_WEBHOOK_SECRET="#{webhook_secret}") if webhook_secret
-
-# Informational message to stderr (won't be eval'd)
-warn ""
-warn "Stripe CLI listening (PID: #{pid})"
-warn "Logs: #{LOG_FILE}"