fix(views): render the dashboard without inline style attributes

[cmer]

Summary

• Remove the last nine inline style attributes from the dashboard views. A nonce cannot rescue a style attribute — those are governed by style-src-attr, which falls back to style-src — so under a strict style-src 'self' the table column widths collapsed and the queue depth bars disappeared. This is the other half of the CSP work started in Emit csp-nonce meta tag so Turbo-injected styles/scripts work under a strict CSP #5.
• Move the fixed column widths and the failed-jobs error cell into role-named rules alongside the other table.fd-data rules in assets-src/input.css (fd-col-select, fd-col-actions, -md, -lg, args.fd-error-cell), and drop the font-size:12px on the processes hostname cell that table.fd-data .dim already sets.
• Render the queue depth bar as a server-rendered SVG, mirroring metrics/_sparkline.html.erb: width on a <rect> is a geometry attribute, so CSP never inspects it. Rounded ends come from border-radius on the SVG root rather than rx, which preserveAspectRatio="none" would stretch. The fd-depth-bar class name is kept so the existing assertion in overview_test.rb still counts real bars.
• Add test/integration/csp_inline_styles_test.rb, which crawls the overview, queues, processes, recurring tasks, /flightdeck/jobs for every JobsQuery::STATES entry, and both a failed and a non-failed job detail page, failing on any rendered style attribute. A second test asserts the overview renders a depth bar with a non-zero width so the first cannot pass vacuously.
• Rebuild the assets (flightdeck-ad6cd9e6c4b8.css → flightdeck-38ba36531cee.css plus manifest.json), add a CHANGELOG.md line under [Unreleased], and regenerate docs/screenshots. Most of the PNG diff is re-seeded data and relative timestamps rather than the style change.

Testing

• bin/test — 283 runs, 0 failures in both the full-host and API-only modes; assets fresh
• bundle exec rake test:system — 13 runs, 48 assertions, 0 failures
• bundle exec rubocop — 91 files inspected, no offenses
• bundle exec rake assets:check — assets are fresh (13 entries)
• bundle exec rake screenshots — all six PNGs regenerated
• Manual check via bin/demo: overview depth bars and every table's column widths, light and dark themes, at 1440px and ~1000px
• Verified the new test is not vacuous by reverting one fix and confirming it fails naming /flightdeck/recurring_tasks