Check-result dropdown with severity badges in node title

[Bilchreis]

Summary

Turns the node title's check-result indicator into an interactive dropdown and
fixes two issues found while verifying it: badge layout breaking on narrow
screens, and the dark theme only half-applying in "system" theme mode.

Changes

Check-result dropdown (secop_components.ex)

• The node title (status icon + equipment name) is now a dropdown trigger.
  Opening it shows all check diagnostics, color-coded by severity, plus the
  SECoP version the node was checked against (scrollable panel, capped at
  max-h-96).
• Next to the title, one badge per severity class shows the diagnostic count
  (e.g. 4 ERROR), sorted most-severe first with matching daisyUI badge
  colors.
• Severity ranking and badge-class mapping are extracted into
  severity_rank/1 and severity_badge_class/1 helpers, replacing the inline
  case duplication.

Responsive badge layout

• The title row now uses flex-wrap, with shrink-0 on the icon and
  shrink-0 whitespace-nowrap on the badges. On narrow viewports badges wrap
  to the next line as whole pills instead of being squeezed until their text
  breaks mid-badge ("4" / "ERROR" on separate lines). This also holds when a
  node has several severity badges.

Dark mode in "system" theme mode (app.css)

• With the theme toggle on "system", daisyUI followed
  prefers-color-scheme (via prefersdark: true) but the Tailwind dark:
  variant only matched an explicit [data-theme=dark] — so daisy-styled UI
  went dark while dark:-styled elements (e.g. the module cards) stayed
  light.
• The dark custom variant now also fires under
  @media (prefers-color-scheme: dark) when no explicit
  [data-theme=light] is set, matching daisyUI's behavior. The
  .command_item dark override gets the same companion media query.
• Explicit light/dark modes are unaffected; explicit light under a dark OS
  stays fully light.

Agent tooling (.claude/skills/run-app/)

• Adds a project skill describing how to run and visually verify the app
  against the user-managed dev server, plus a Playwright-based screenshot
  helper that waits for LiveView/ECharts content before capturing.
  Playwright itself is not a project dependency — the helper resolves it from
  the invoking directory (agent scratchpad).

Verification

Verified against the running dev server with headless Chrome at multiple
viewport sizes:

• Dropdown badges stay intact as whole pills at narrow widths (1080px) with
  the 4-error sim node selected.
• System + OS-dark now renders module cards dark; system + OS-light and both
  explicit modes unchanged.