Walkthroughs: stop autoplaying muted, and show the length

Marty asked why they start muted. Browsers only permit autoplay when a video
is muted, so "expand and play" necessarily meant "expand and play silently" —
and for these that is the wrong trade, because the narration IS the training.
A member's first visit was showing them a silent walkthrough.

So the panel now opens paused with the play button showing. Pressing it is a
user gesture, which means it plays with sound, every time. preload stays
'none' until the panel opens, then goes to 'metadata' so an open panel shows
a real first frame instead of a black rectangle.

Each bar now also carries its runtime ("· 71 sec"), so nobody has to guess
whether they are committing to one minute or ten.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

public/suite-email.html

@@ -58,6 +58,6 @@
   <p class="em-note"><strong style="color:var(--text)">Teach it forward:</strong> a member with a follow-up sequence running never loses a warm prospect to silence — show your two how to set theirs up. <br>Read every email before you send it; your name is on it. Generated copy follows the team's rules — no income promises, no invented numbers, honest about risk. Independent team resource · No income is guaranteed · Cryptocurrency involves risk.</p>
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 <script src="/suite-email.js"></script>
-<script src="/tool-video.js" data-video="/tv/suite-email-engine.mp4" data-title="Watch the Email Engine walkthrough" data-key="email" defer></script>
+<script src="/tool-video.js" data-video="/tv/suite-email-engine.mp4" data-secs="· 42 sec" data-title="Watch the Email Engine walkthrough" data-key="email" defer></script>
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