feat: Pioneer-sourced EVM chain registry + Solana sign-message UX

[BitHighlander]

Summary

• Pioneer-sourced EVM chain registry replacing the static EIP155_CHAINS table. chains.ts is deleted; chain metadata + RPC URLs come from GET /api/v1/discovery/caip/{caip} on demand, in-memory cached (1h TTL on hits, 1m on misses, inflight coalescing). Closes the three-way mismatch where the network dropdown advertised BNB Smart Chain but wallet_switchEthereumChain rejected it because chains.ts was missing eip155:56.
• One-step add+switch in wallet_switchEthereumChain — when Pioneer recognizes the chain (~196 EVMs today), we provision the provider, persist to blockchainDataStorage, and switch immediately. The chain-not-enabled card is now a true last resort (Pioneer also doesn't know it) instead of the default response to "you didn't pre-register this chain."
• Friendly fallback popup — ChainNotEnabledCard shows the requested chainId, the dApp URL, and a Chainlist link. Surfaces in the side panel before the EIP-3326 4902 still goes back to the dApp.
• Solana sign-message popup polish — was rendering "Unknown Method / TO: N/A / AMOUNT: N/A". Now decodes the message bytes (UTF-8 with hex fallback), shows the actual text the dApp is asking the user to sign, and labels the request "Sign Solana Message" with appropriate copy for signMessage / signOffchainMessage / signTransaction / signAndSendTransaction.
• Hardware-friendly timeouts — vault Solana sign endpoints bumped 30s→300s (matches the injected-script callback ceiling, so the vault never aborts before the user can act).
• Friendlier timeout error UI — yellow "Took too long" warning with retry-from-dApp guidance instead of red "Error Occurred" panel.

Files

• New: chrome-extension/src/background/chains/registry.ts — Pioneer chain catalog client
• New: chrome-extension/src/background/popup.ts — openSidePanel / setApprovalBadge extracted (breaks circular import between methods.ts and chain handlers)
• New: pages/side-panel/src/approval/ChainNotEnabledCard.tsx
• Deleted: chrome-extension/src/background/chains.ts
• Modified: ethereumHandler.ts (switch handler rewrite), index.ts (5 call sites + Pioneer-sourced default provider), solanaHandler.ts (timeouts), Transaction.tsx, RequestMethodCard.tsx, RequestDetailsCard.tsx, methods.ts (helper imports), feeFloors.ts (comment)

Test plan

• Reload extension → BSC switch from a dApp (e.g. pump.fun, app.uniswap.org) succeeds in one round trip; BNB Smart Chain auto-appears in the network dropdown
• Switch to a Pioneer-known chain you haven't visited before (e.g. Mantle 0x1388, Linea 0xe708) — should add+switch in one step
• Switch to a Pioneer-unknown chainId (e.g. 0xfffffe) — chain-not-enabled card surfaces with Chainlist link, dApp gets 4902
• User-added custom networks (Add Network UI) still take precedence over Pioneer (custom RPC overrides honored)
• ETH default provider initialization works on a fresh install (no web3ProviderStorage entry yet)
• Solana signMessage from a dApp shows "Sign Solana Message" with the actual decoded message text in the popup
• Solana sign request that takes >30s no longer errors; can complete up to 5 minutes
• Trigger a sign-message timeout — popup shows yellow "Took too long" card, not the red error panel

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