feat: add native circle authoring UI

[tomismeta]

Adds native circle authoring to the existing circles page, exposing the existing sealed circle deploy and encrypted asset upload flows through the webcli UI.

Changes:

• Adds browse, deploy, and upload tabs to static/circles.html.
• Adds a circle deployer view for sealed octb circle deployment with fixed protocol defaults and editable fee.
• Adds a circle asset upload view for one encrypted asset per transaction, including circle id, file picker/drop zone, path, content type, key id, sealed read passphrase, padding class, and fee.
• Adds confirmation dialogs before deploy/upload signing.
• Shows locked-wallet feedback before signing with unlock wallet first.
• Populates browse/upload fields after successful deploys and uploads.
• Links submitted transaction hashes to the configured explorer URL.
• Fixes nullable optional deploy fields in /api/circle/deploy.
• Derives and validates the deployed circle id server-side before signing.
• Improves RPC error messages for oversized or non-JSON RPC responses.

Validation:

• Built with ./setup.sh.
• Ran git diff --check.
• Ran inline JS parse check for static/circles.html.
• Verified the UI on http://127.0.0.1:8421/circles.html.
• Manually tested devnet circle deploy and encrypted asset upload using address octAaLHDf3HNaNMJr41j79knWk7WTX6JwgzAcHTZYm1ZCQF.
• Verified locked-wallet deploy/upload paths do not proceed to signing.

[tomismeta]

Added screenshots of the new circles authoring flow.

Browse

Existing circle viewer flow preserved: paste an oct://... URI or circle id, enter a sealed read passphrase when needed, and open the resource.

Deploy

New native circle deployer tab. It keeps the deploy defaults intentionally narrow for sealed native circles, shows the protocol settings before signing, and requires an explicit confirmation before submitting.

Upload

New encrypted asset upload tab. It supports one selected asset per transaction, shows the target circle id, path, content type, key id, passphrase field, padding class, fee, and requires confirmation before signing.

[tomismeta]

Updated against latest main and squashed to one commit. This preserves the original PR's scope, while calibrating to new/adjacent public/plain circle features.

circles.html now has native browse, deploy, and upload tabs for circle authoring using the existing circle APIs and webcli UI style. It supports deploying sealed_read and public_resources circles, uploading encrypted assets to sealed_read circles, uploading plain assets to public_resources circles, and calculating tier-based asset upload fees.

No backend/RPC changes. I intentionally did not wire the newly introduced low-level circle policy/state/object/relay APIs; those are better suited to separate feature-level PRs.