feat(networks): add 5 EVM testnets from metadata v1.2.1-alpha.0

[AugustoL]

Description

Adds 5 EVM testnets introduced in explorer-metadata PR #16 (released as @openscan/metadata@1.2.1-alpha.0): Arbitrum Sepolia (421614), Optimism Sepolia (11155420), Base Sepolia (84532), Polygon Amoy (80002), and Avalanche Fuji (43113).

Each new chain ID is routed to its L1 family's adapter so block/tx/account pages render the right L2-specific fields (Arbitrum l1BlockNumber/sendCount/sendRoot, OP/Base l1Fee/l1GasPrice/l1GasUsed).

Related Issue

N/A — follows explorer-metadata#16.

Type of Change

• New feature
• Bug fix
• Documentation update
• Refactoring
• Performance improvement
• Other

Changes Made

• Bump METADATA_VERSION to 1.2.1-alpha.0 (src/services/MetadataService.ts) — fetches refreshed RPCs, new testnet RPC lists, and new logos from jsDelivr. Also acts as localStorage cache-bust.
• Add 5 testnet entries to src/config/networks.json with slugs arb-sepolia, op-sepolia, base-sepolia, polygon-amoy, avax-fuji, each marked isTestnet: true with logo, color, currency, and faucet/bridge/docs links.
• Register testnets in AdapterFactory (src/services/adapters/adaptersFactory.ts):
  • 421614 → ArbitrumAdapter
  • 11155420 → OptimismAdapter
  • 84532 → BaseAdapter
  • 80002 → PolygonAdapter
  • 43113 → EVMAdapter (same as Avalanche mainnet)
• Work around missing ClientFactory support (src/services/DataService.ts) — @openscan/network-connectors does not yet register these testnet chain IDs in its CHAIN_REGISTRY, which would cause ClientFactory.createTypedClient to throw at runtime. DataService now instantiates the L1 family's client directly for the 5 testnet chain IDs via an EVM_TESTNET_CLIENTS lookup (they share the same JSON-RPC surface).
• Widen AppChainId and L2 adapter constructor types to accept the new testnet chain IDs alongside their mainnet pair (42161 | 421614, 10 | 11155420, 8453 | 84532, 137 | 80002).
• Tighten PolygonAdapter constructor type from SupportedChainId to 137 | 80002 to match sibling L2 adapters (refactor commit).

Screenshots

N/A — CDN-sourced logos and existing EVM page layouts.

Checklist

• I have run npm run format:fix and npm run lint:fix
• I have run npm run typecheck with no errors
• I have run tests with npm run test:run (88/88 pass)
• I have tested my changes locally
• I have updated documentation if needed (no doc surface changed)
• My code follows the project's architecture patterns

Additional Notes

• No changes to BUILTIN_RPC_DEFAULTS (src/utils/rpcStorage.ts): the new testnets fetch RPCs purely from the metadata CDN, matching the pattern used by Sepolia and BSC Testnet.
• Follow-up for @openscan/network-connectors: once the library registers these 5 chain IDs in its CHAIN_REGISTRY, the EVM_TESTNET_CLIENTS workaround in DataService.ts can be removed and the widened types collapsed back.
• Verification steps for reviewers:
  1. DevTools → Application → Local Storage: clear OPENSCAN_METADATA_RPCS, reload, confirm the new cache entry's version is "1.2.1-alpha.0".
  2. Navigate to /arb-sepolia, /op-sepolia, /base-sepolia, /polygon-amoy, /avax-fuji and confirm each network dashboard loads with block number + gas price.
  3. On Arb Sepolia, open a recent block detail and verify l1BlockNumber renders; on OP/Base Sepolia open a transaction and verify L1 fee fields.
  4. Settings → RPCs tab lists the new endpoints with tracking/isOpenSource metadata from v1.2.1.

[github-actions]

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