Perf/dashboard endpoint optimization (#1897)

* optimize net_category_totals() by using memoized cache

* fix issue - net_category_totals cache is never populated - suggested by coderabbitAI

* fix 422 error for service-worker

* remove warning of [assigned but unused variables] - income_statement.rb

* remove warnings of [assigned but unused] from Prism - income_statement_test.rb

* add some measurements to improve docstring coverage, follow CodeRabbit recommendation

* attach Skylight monitoring for dev env as well - use my own Skylight auth token

* integrate Skylight with my own account auth token for local benchmark

* fix PR review suggestion - Move fallback release-note copy to i18n keys

* follow PR review - Fix changelog GitHub fetch timeout bounding

* FIX - Variable shadowing; Prefer stubbing the specific instance over any_instance.expects

* fix CodeRabbit feedback - Reusing the same stub for both classifications hides a contract mismatch

* fix CodeRabbit FEEDBACK - Reconsider enabling Skylight by default in development

* fix CodeRabbitAI FEEDBACK - reconsider unconditionally enabling Skylight in development

* fix Security scan FEEDBACK before PR merge

* fix jjmata feedback

app/controllers/pages_controller.rb

@@ -49,9 +49,9 @@ class PagesController < ApplicationController
       @release_notes = {
         avatar: "https://github.com/we-promise.png",
         username: "we-promise",
-        name: "Release notes unavailable",
+        name: t("pages.release_notes_unavailable.name"),
         published_at: Date.current,
-        body: "<p>Unable to fetch the latest release notes at this time. Please check back later or visit our <a href='https://github.com/we-promise/sure/releases' target='_blank'>GitHub releases page</a> directly.</p>"
+        body: t("pages.release_notes_unavailable.body_html")
       }
     end