feat: add walletconnect and injected dapp provider with approval flow

[digitalSloth]

Adds WalletConnect pairing and a read-only injected window.zenon provider, with a shared approval flow for dApp signing requests.

Core:

• account-block-params, account-block-validation, message-guard, message-signing: validate and decode dApp signing requests, including contract-call data previews
• dapp-approvals, site-permissions, inpage-protocol, inpage-approval-bridge: approval queue, per-site permissions and the inpage message protocol
• walletconnect-service, walletconnect-client, walletconnect-sign-client-adapter, storage/walletconnect-storage: WalletConnect sessions and persistence

Extension:

• content-script.ts, inpage.ts: inject window.zenon with read-only and prompting provider methods
• sw/: service-worker router, ports, approval inbox and public state
• approve.html, ApproveApp.vue, approve-main.ts: approval window opened as a popup

UI:

• pages/WalletConnect.vue, DappApprovalDialog.vue, SettingsDialog.vue: pairing, session list and approval dialog
• composables: useWalletConnect, useDappApprovals, useConnectedSites

Also updates manifest, build configs, router, package.json and the README.