feat: add Loading component and loading states

[Ehsan-saradar]

Summary

Adds a reusable <Loading> component and wires it into pages that previously rendered with empty data while async fetches were in flight. The goal is to give users a clear visual signal that data is being fetched, rather than a flash of empty cards.

Changes

• src/components/Loading.vue (new): centered spinner + text inside an optional bg-base-100 card. Props: height, size, text, bordered. Use :bordered=\"false\" to embed inside an existing card that already has its own title and background.
• Block detail (/<chain>/block/:height): replaces the side-effect-in-computed pattern (where isFutureBlock was triggering fetchBlock) with a proper onMounted lifecycle hook and explicit loading state. Also ensures store.latest is loaded before deciding whether to treat a height as a future block, so the user no longer sees empty "Block Header" / "Transactions" / "Last Commit" cards on first paint.
• Dashboard (/<chain>): Active Proposals, Application Version, and Node Information now show a loading row inside their cards while keeping titles visible. The proposals loading state is sourced from the existing useGovStore().loading['2'] LoadingStatus tracking.
• IBC Connection detail (/<chain>/ibc/connection/:id): top connection header (chain IDs, state, counterparty) stays visible; IBC Client and Channels sections show loading inside their cards while their async RPC calls are in flight.
• Supply (/<chain>/supply): table headers stay visible, body is replaced with loading row during initial fetch and during page changes.
• Parameters (/<chain>/params): per-section loading for Chain ID, Staking, Governance, Distribution, Slashing, Application Version, and Node Information. Each section is awaited independently so loading reflects only that section.
• CardParameter: accepts a new optional loading prop. When set, the card still renders (title visible) and shows the loading component instead of the value grid.
• Bug fix in useParamsStore.handleGovernanceParams: the Promise.all for voting/deposit/tally params was previously not awaited, so the action resolved before gov.items was populated. This made .finally()-based loading tracking fire too early. Now awaited correctly.

Test plan

• Hard refresh /<chain>/block/<height> — should show a single loading card, then the populated block data (no empty cards flash)
• Hard refresh /<chain> — Active Proposals, Application Version, and Node Information sections show titles + loading until data arrives
• Visit an IBC connection detail page — connection header is visible immediately; IBC Client and Channels sections show loading until data arrives
• Visit /<chain>/supply and click pagination — table headers stay visible, loading row appears during fetch
• Visit /<chain>/params — each section independently shows loading and resolves to data
• Visit a chain with governance excluded — Governance Parameters card finishes loading and stays hidden (since items.length === 0)