v0.9.0: UI redesign + stricter end-to-end test verification

=== UI redesign (zero new deps, same binary size) ===

Entire App::update() rewritten around three ideas:

1. Section cards. Form rows are grouped inside rounded frames with
   faint fills and small-caps headings:
     - 'Apps Script relay'  — Deployment IDs (textarea) + Auth key
     - 'Network'            — Google IP (+inline scan button), Front
                              domain, Listen host, HTTP+SOCKS5 ports
                              on one row, SNI pool button
     - Collapsing 'Advanced' — upstream SOCKS5, parallel dispatch,
                              log level, verify SSL, show auth key.
                              Closed by default — most users never
                              touch these.

2. Clearer action hierarchy. Primary buttons are accent-filled and
   larger:
     - Start  (green filled,  ▶ glyph, 120x32)
     - Stop   (red filled,    ■ glyph, 120x32)
     - Save config (blue accent filled, path shown inline after →)
     - SNI pool (blue accent filled, inside Network section)
     - Test relay (neutral, tall)
   Secondary actions (Install CA / Check CA / Check for updates)
   moved to their own compact row below, no longer competing.

3. Status + log clarity.
   - Header version links to GitHub:  → repo,  →
     the release tag page.
   - Running/stopped status is now a pill-shaped colored chip at the
     right end of the header (green fill + green dot when running,
     red when stopped).
   - Traffic stats in a 2-column layout inside the Traffic card —
     7 metrics fit in 4 rows instead of a 7-row vertical strip.
   - One compact transient status line above the log that auto-hides
     after 10 seconds — replaces the previous stack of permanent
     ca_trusted / test_msg / update_check labels that were pushing
     the log panel off-screen.
   - Log panel now has its own bordered frame (darker fill), a
     '[x] show' checkbox that hides it entirely when off, a 'save…'
     button that writes the current log buffer to a timestamped
     log-YYYYMMDD-HHMMSS.txt in the user-data dir, and a 'clear'
     button. Empty state shows a muted placeholder instead of
     silent void.

All helper functions (section, primary_button, form_row) live at the
top of ui.rs as small local helpers — no new modules, no new
dependencies.

=== Stricter end-to-end test (test_cmd.rs) ===

Previous test passed on any HTTP 200 status regardless of body.
After a user pointed out that the test reported PASS even after
they deleted their Apps Script deployment, updated the pass criteria:

  1. Status must contain '200 OK'.
  2. Body must parse as JSON.
  3. JSON must have an 'ip' field with a valid IPv4 or IPv6.

Anything else → SUSPECT (returns false), with a specific log message
like 'HTML returned instead of JSON. The Apps Script deployment may
be deleted, not published to Anyone, or requires sign-in.'

Also now emits tracing::info!/warn!/error! alongside println!, so
the verdict + detail show up in the UI's Recent log panel instead
of disappearing to a stdout nobody sees.

One new unit test: looks_like_ip() accepts v4+v6, rejects empty,
rejects malformed, rejects overflowed octets. 44 tests total, all
green.

Verified locally end-to-end — UI launches clean, form loads config
cleanly, Start/Stop/Save all fire correctly, Test relay produces
the new PASS/SUSPECT verdict with the tracing detail visible in
the log panel, Check-for-updates hits GitHub and resolves with the
compact auto-hiding status line.

Cargo.lock

@@ -1317,7 +1317,7 @@ dependencies = [
 
 [[package]]
 name = "mhrv-rs"
-version = "0.8.6"
+version = "0.9.0"
 dependencies = [
  "base64 0.22.1",
  "bytes",