fix(insights): one card language on the sub-page spine

A measured pass over every insights sub-page, the dashboard, and the
settings sections (computed text colour, left text edge relative to the
card edge, header→body distance, per card) surfaced the drift the eye
kept catching:

- The blood-pressure pulse-pressure/MAP explainer was a bare muted
  paragraph at the container edge, 16–24 px left of every neighbouring
  card's text. It now rides a compact Card in the regular foreground.
- The 'Usual range' read strip was a hand-rolled bg-card/60 shell with
  its own padding; rebuilt on Card + TileHeader + CardContent at the
  compact density so background, radius, icon spacing and text edge
  match the neighbouring tiles.
- The spine tiles carried three different header→body distances (6, 12
  and 24 px) via off-scale overrides (gap-1.5, md:gap-3, md:py-5,
  gap-3). Assessment, target summary, medication tiles, the mood
  stand-out card and the sleep hypnogram now share the sanctioned
  compact tier (gap-2 py-3 md:py-4).
- The hero score card and its skeleton kept their translucent identity
  but move from a static px-4 py-4 to the p-4 md:p-6 card norm, putting
  their text on the same edge as every other card.
- Two dashboard shells (recent workouts, recent unlocks) froze at p-4
  on every breakpoint; now p-4 md:p-6.
- Settings: the modules hint moves into the header's description slot
  and the injection-site grid joins the section-wide mt-4 rhythm — the
  two gaps that deviated from the settings 16 px header→content norm.

src/components/settings/injection-sites-card.tsx

@@ -73,7 +73,7 @@ export function InjectionSitesCard({
         title={t("settings.globalExcludedInjectionSitesLabel")}
         description={t("settings.globalExcludedInjectionSitesHint")}
       />
-      <div className="mt-3 grid grid-cols-1 gap-2 pl-7 sm:grid-cols-2">
+      <div className="mt-4 grid grid-cols-1 gap-2 pl-7 sm:grid-cols-2">
         {INJECTION_SITE_KEYS.map((site) => (
           <label key={site} className="flex items-center gap-2 text-sm">
             <Checkbox

src/components/settings/modules-section.tsx

@@ -121,16 +121,15 @@ export function ModulesSection() {
   // was removed: a domain that can't be turned off doesn't need to be listed.
   return (
     <SettingsCard>
+      {/* The "what this section does" hint rides the header's standard
+          description slot; the body follows at the settings-wide mt-4
+          header→content rhythm instead of the former mb-2/mb-3 one-offs. */}
       <SettingsCardHeader
         icon={Blocks}
         title={t("settings.sections.modules.toggleable.title")}
-        className="mb-2"
+        description={t("settings.sections.modules.toggleable.description")}
       />
-      {/* v1.18.6 — restore the one-line "what this section does" hint. */}
-      <p className="text-muted-foreground mb-3 pl-7 text-sm leading-relaxed">
-        {t("settings.sections.modules.toggleable.description")}
-      </p>
-      <div className="divide-border divide-y pl-7">
+      <div className="divide-border mt-4 divide-y pl-7">
         {(Object.keys(MODULE_REGISTRY) as ModuleKey[])
           // Modules switched off in code (pending a rebuild) carry no live
           // toggle — drop the row entirely so a user can't turn one on.