fix(settings): About + API surfaces — restructure, fix update check, fit tables

Bucket B of the v1.4.3 polish pass.

Three issues, one commit because they're the same surface:

1. **API & Tokens tables overflowed the settings content column.**
   Each table set `min-w-[760px]` (or 860px) so the table never
   compressed below that width. On mobile this is intentional (it
   gives the inner cells breathing room while the outer wrapper
   horizontally scrolls). On md+ the parent column is smaller than
   the min-width on common laptop sizings (~800px content area when
   the browser isn't full-width), which forced an inline scrollbar
   for no benefit. Switched to `min-w-[760px] md:min-w-0` per table
   so the constraint releases at the breakpoint where the layout
   stops scrolling.

2. **"Auf Updates prüfen" button silently did nothing.** The
   client-side handler called `https://api.github.com/.../releases/
   latest` directly. Production CSP locks `connect-src` down to
   `'self'` + `https://wbsapi.withings.net`, so the fetch was
   blocked at the browser before it left the tab. Replaced with a
   server-side proxy at `/api/version/check-updates` that fetches
   GitHub for the user, compares the running `package.json` version
   against `tag_name`, and returns one of `up_to_date | newer_
   available | unknown`. The route is auth-gated (cookie OR bearer)
   so anonymous traffic can't burn through GitHub's 60-req/hr anon
   rate limit on the deployment's IP. The route also annotates the
   external call into the Wide Event so a future spike is visible
   in the logs.

3. **The About surface had no headings and a stray Badge box.** The
   v1.4.2 version put the License inside a `<Badge variant=
   "outline">`, which created a small framed pill that read as a
   separate widget rather than a peer of the version number. Below
   that, the Sources/Changelog/Docs and the update-check button
   each lived in their own card with no h2 — three nameless cards
   stacked on the page. Restructured into three titled cards:

     - **HealthLog** — identity, with version + license rendered
       inline as plain monospace pairs (no Badge, no nested grid).
       Build SHA + build timestamp ride along on the same row when
       set.
     - **Quellen & Dokumentation / Sources & docs** — links unchanged
       but now under their own h2.
     - **Updates** — manual `Check now` button + a passive "Last
       checked: …" line that pulls from localStorage so the user
       can see when the previous check ran. On mount, if the last
       successful check is >24h ago (or has never run), the page
       auto-checks once. The 24h window is a deliberate compromise
       between "always fresh" and "GitHub anon rate limit". The
       error path renders a non-blocking "Couldn't reach GitHub"
       message with the alert role so screen readers announce it.

i18n keys touched in both `de.json` + `en.json`:
  - `settings.about.linksHeading` (new)
  - `settings.about.updatesHeading` (new)
  - `settings.about.checkUpdates` (label shortened)
  - `settings.about.checking` (button busy state — new)
  - `settings.about.lastChecked` / `lastCheckedNever` (new)
  - `settings.about.checkFailed` (new — replaces the misleading
    `testConnection.errors.connection_failed` reuse)

Tests updated for the new heading + button strings; 669/669 green.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/settings/api-section.tsx

@@ -71,7 +71,7 @@ function ApiEndpointsCard() {
       </p>
 
       <div className="border-border mt-4 overflow-x-auto rounded-lg border">
-        <table className="w-full min-w-[760px] text-xs">
+        <table className="w-full min-w-[760px] text-xs md:min-w-0">
           <thead>
             <tr className="bg-muted/40 text-muted-foreground border-b">
               <th className="px-3 py-2 text-left font-medium">
@@ -237,7 +237,7 @@ function ApiTokensCard() {
             {t("settings.activeTokensTitle")}
           </p>
           <div className="border-border overflow-x-auto rounded-lg border">
-            <table className="w-full min-w-[860px] text-sm">
+            <table className="w-full min-w-[860px] text-sm md:min-w-0">
               <thead>
                 <tr className="bg-muted/40 text-muted-foreground border-b text-xs">
                   <th className="px-3 py-2 text-left font-medium">
@@ -360,7 +360,7 @@ function ApiTokensCard() {
             </button>
             {showRevokedTokens && (
               <div className="border-border overflow-x-auto rounded-lg border">
-                <table className="w-full min-w-[760px] text-sm">
+                <table className="w-full min-w-[760px] text-sm md:min-w-0">
                   <thead>
                     <tr className="bg-muted/40 text-muted-foreground border-b text-xs">
                       <th className="px-3 py-2 text-left font-medium">