Fix : Gateway staging feedback fixes

[sk-enya]

• Dev Tools are not accessible from the footer.
• In the Ecosystems section I see two extra scrollbars in addition to the default one; the same issue appears in the Trade section.
• DAO ▸ Delegate vote: If the user opens the MetaMask popup and then closes it without signing, the dApp doesn’t handle the rejection gracefully—an error like User rejected the request … MetaMask Tx Signature: User denied transaction signature. is shown and the delegate-vote popup UI breaks.
• DAO ▸ Delegate vote: When the user selects “To Someone Else,” enters a target address, and then clicks “Myself,” the dApp still remembers the previously entered address. The address field should reset when switching back to “Myself.”
• DAO ▸ Create proposal: The banner reads “At least 0 BOBA + xBOBA are needed to create a new proposal.” Displaying “0 BOBA” is confusing.
• DAO ▸ Create proposal ▸ Change voting threshold: The Target address field is not validated, so the user can enter any value. An error only appears after clicking Delegate vote. Validate the address before enabling the action button.
• Navigating directly to a nonexistent path (e.g., https://staging.gateway.boba.network/assets/) should return a well-styled 404 Not Found page; currently a broken page is rendered instead.
• The proposal list in the DAO section is inconsistent—sometimes all proposals load, other times none appear.