Product page: lifetime price, rounded usage, roadmap (#126)

## Summary
- Closes #123.
- Hide account and document counts until there are 20 accounts. After that, both figures round down to one significant digit and show a plus, so the page never publishes an exact count.
- The product page and pricing page say early adopters pay $10 per month, locked for the lifetime of the account, and that price never goes up.
- The product page adds a roadmap section for image generation and vision.

## Test plan
- [ ] With fewer than 20 accounts, the product page shows no usage figures.
- [ ] With 23 accounts and 156 documents, the page shows 20+ accounts and 100+ documents stored, plus the as-of date.
- [ ] The product page states the lifetime $10 lock and lists image generation and vision under Roadmap.
- [ ] The pricing page states the same lifetime lock.

Reviewed-on: #126

llm-fe/public/index.html

@@ -83,7 +83,7 @@
 </head>
 
 <body>
-  <div id="root"><h1>Hesychia is a calm AI assistant.</h1><div id="crawler-prose"><p>Quiet, focused AI chat — private by default — is how this Hesychia product is built.</p><p>It remembers what you told it and your documents, so you never start over, and conversation memory is a setting you control.</p><p>We store your account, your conversations, and the documents you upload.</p><p>We do not sell your data, and we do not use advertising cookies.</p><p>Canceling does not delete documents, and they stay until you delete them or delete the account, and account deletion is a soft-delete.</p><p>It remembers what you told it and your documents, so you never start over.</p><p>Your documents stay stored and searchable, and answers are grounded in your own files.</p><p>Business accounts are simple management for your team, and company managers can manage team accounts.</p></div><nav aria-label="Related pages"><a href="/pricing/">Hesychia pricing — $10/month, no ads</a><a href="/privacy/">What Hesychia stores and does not sell</a><a href="/changelog/">Dated Hesychia product updates</a><a href="/terms_of_service/">Hesychia terms of service</a><a href="/account-deletion/">How to request Hesychia account deletion</a></nav></div>
+  <div id="root"><h1>Hesychia is a calm AI assistant.</h1><div id="crawler-prose"><p>Quiet, focused AI chat — private by default — is how this Hesychia product is built.</p><p>It remembers what you told it and your documents, so you never start over, and conversation memory is a setting you control.</p><p>We store your account, your conversations, and the documents you upload.</p><p>We do not sell your data, and we do not use advertising cookies.</p><p>Canceling does not delete documents, and they stay until you delete them or delete the account, and account deletion is a soft-delete.</p><p>It remembers what you told it and your documents, so you never start over.</p><p>Your documents stay stored and searchable, and answers are grounded in your own files.</p><p>Business accounts are simple management for your team, and company managers can manage team accounts.</p><p>Early adopters pay $10 per month, locked for the lifetime of the account, and that price never goes up.</p><p>Image generation is on the roadmap, so a prompt can create a picture inside Hesychia.</p><p>Vision is on the roadmap, so you can ask questions about an image you upload.</p></div><nav aria-label="Related pages"><a href="/pricing/">Hesychia pricing — $10/month, no ads</a><a href="/privacy/">What Hesychia stores and does not sell</a><a href="/changelog/">Dated Hesychia product updates</a><a href="/terms_of_service/">Hesychia terms of service</a><a href="/account-deletion/">How to request Hesychia account deletion</a></nav></div>
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