Add Sentry Logs observability and memory tracker middleware

[JuanVqz]

Context

Web dyno is hitting R14 continuously (average 114% quota, peak 209%). We are investigating the memory leak. This PR adds observability tooling to identify the source and reduces Sentry noise/memory pressure from the current capture_message approach.

Changes

capture_message -> Sentry.logger.info on all legacy traffic endpoints

All seven Sentry.capture_message calls replaced with Sentry.logger.info. Hits now land in Sentry Logs instead of firing Slack alerts and burning event quota. Extra debug fields added per endpoint to help answer who is hitting what:

Endpoint	New fields
POST /gems	method, path, format
GET /gems/:id	format (crawler vs API consumer)
GET /gems/compat_table	gemmy_count (spot bulk callers)
GET /gems/:gemmy_id/compatibility/:id	renamed gemmy_id -> gem_name
POST /api/github_notifications	check_name, status (full check_run state)
POST /api/results	success field (was checker reporting success or failure?)
POST /api/releases	renamed name -> gem_name for consistency

MemoryTracker rack middleware (new)

app/middleware/memory_tracker.rb reads /proc/$PID/status VmRSS before and after each request. When a single request grows RSS by 5+ MB it logs to Sentry.logger.warn with:

rss_before_mb, rss_after_mb, delta_mb, method, path, query_string, remote_ip, user_agent, referer

This will pinpoint exactly which endpoint and which request parameters are growing memory. The /proc read is Linux-only (Heroku dynos); the rescue fallback returns 0.0 so it is silent locally on macOS.

config/initializers/sentry.rb tuning

Three changes to reduce Sentry's own memory footprint:

• Removed enabled_patches: [:logger] - was routing every Rails.logger call through Sentry's breadcrumb buffers, holding string references for the lifetime of each request
• Added max_breadcrumbs: 20 - caps per-request breadcrumb buffer (default was 100)
• Changed include_local_variables: false - was capturing all local variable values on every exception, which can hold large ActiveRecord objects in Sentry's internal buffers

Sentry gem version alignment

sentry-rails and sentry-sidekiq bumped from ~> 5.5 to ~> 6.5 to match sentry-ruby ~> 6.5. Having sentry-ruby 6.x with sentry-rails 5.x was a version mismatch.