Solo product family: homepage redesign and top navigation structure

[Reccetech]

Summary

Solo Provisioner (Weaver) and Solo Operator are being migrated from the Hashgraph org to the Hiero org and will join Solo CLI under the solo.hiero.org umbrella. The site currently has no awareness of a product family. This work establishes the structure before content arrives so each product's docs can slot in cleanly.

Proposed Changes

1. Homepage redesign

• Add a product family landing section with a quick-link card for each product (Solo CLI, Solo Provisioner, Solo Operator)
• Each card links to that product's docs section
• Add a brief "Which Solo product do I need?" orientation — 2–3 sentences per product on audience and use case

2. Top navigation bar

• Add top-level nav switching between the three product doc sections
• Provisioner and Operator entries can initially point to placeholder landing pages while migration is in progress
• Solo CLI entry is the existing docs structure — no content changes needed

Dependencies / Open Questions

• One-line descriptions and audience framing for Provisioner and Operator need input from migration owners
• Confirm whether Provisioner and Operator docs will live in this repo or separate repos with cross-links
• Confirm Q3 timeline for the Hiero migrations

Related: #34 (Provisioner content), #241 (Examples Hub restructure)