feat(tangle-cloud): restore Tangle dapp design system

[drewstone]

Summary

• Restores the original Tangle dapp chrome/action hierarchy in Tangle Cloud: visible wallet/network controls, no duplicate Blueprints top-nav title, normal button typography, and no action-dot artifacts.
• Rebuilds the Blueprints page as a list-first infrastructure catalog with default blueprint visuals, capacity/trust/source/usage columns, mobile cards, and tighter add-capacity drawer behavior.
• Hardens Cloud network/data behavior by normalizing local-preview default state to Base Sepolia, aligning audited-status and indexer-health reads with the selected network, and adding blueprint query cache retention.
• Adds a product-brief note and dated design-audit trace for the design decision and browser verification artifacts.

Verification

• NX_DAEMON=false NX_SKIP_NX_CACHE=true yarn nx typecheck tangle-cloud
• NX_DAEMON=false NX_SKIP_NX_CACHE=true yarn nx test tangle-cloud
• NX_DAEMON=false NX_SKIP_NX_CACHE=true yarn nx build tangle-cloud
• git merge-tree --write-tree origin/develop HEAD
• Pre-push hook: full repo lint/test/build completed successfully
• Playwright browser audit screenshots in /tmp/tangle-cloud-dapp-system-audit/: desktop dark/light, mobile dark, instances, add-capacity drawer

Browser counters after fixes: local8545=0, local8080=0, Radix ref warnings 0, italic controls 0, measured overflow 0.