Restructure docs navigation around user intent

[HDauven]

Summary

• reorganize the documentation around four reader intents: Learn, Use Dusk, Build, and Operate
• replace implementation-shaped sidebar buckets with task-oriented groups
• add a concise Use Dusk entry page for wallets, staking, bridges, migration, and explorers
• consolidate Dusk Wallet, Web Wallet, Rusk Wallet, and community wallet guidance into one comparison page
• keep workflow instructions in dedicated task guides and upstream command references
• document official mainnet/testnet explorers and clearly distinguish community-operated alternatives
• refocus the Ecosystem page on third-party applications, wallets, network tools, initiatives, and integrations
• align homepage, developer, operator, and machine-readable entry points with the new navigation

Rationale

The previous structure reflected how pages had accumulated rather than what readers were trying to do. User workflows were mixed into Learn, wallet products and developer integrations were easy to conflate, and thin product pages repeated instructions already covered by task guides or versioned upstream documentation.

The new structure separates conceptual learning, end-user actions, application development, and infrastructure operation. Wallet selection now happens in one place; migration, bridging, staking, and node setup remain independently maintained workflows; and community projects are listed in a clearly disclaimed ecosystem directory.

Compatibility

• the canonical new routes are /use/overview/ and /use/wallets/
• /learn/web-wallet/ redirects to the Web Wallet section
• /learn/rusk-wallet/ redirects to the Rusk Wallet section
• /use/dusk-wallet/ redirects to the Dusk Wallet section for compatibility with the earlier draft
• all other existing content routes remain valid

Validation

• npm run build
• 59 pages built and 86 HTML files indexed
• all internal links valid
• all 56 sidebar destinations return 2xx from the local server
• canonical pages and compatibility redirects tested locally
• wallet, explorer, and ecosystem destinations checked directly
• git diff --check