cardano-wasm demo: multi-wallet management

[palas]

Context

This is a follow up to: #1257

It adds the initial functionalities of the demo:

• generate stake-enabled wallets; restore from bech32 signing keys
• editable alias, collapsible cards, keys & hashes (blurred secrets), copy address, forget dialog
• mainnet/preprod/preview switch with wasm address re-derivation
• console panel (capped, scroll pinned to newest) and toast
• module skeleton: Types, State, Update, View, Wasm, Net, Format, Ports

How to trust this PR

• Diff is entirely cardano-wasm/demo/ + a changelog fragment; CI already compiles it (elm make --optimize) and checks elm-format.
• To try it: serve this PR's cardano-wasm-demo artifact over http and click through.
• No network requests, no persistence; all key/address work is cardano-wasm calls (see web/ports.js).
• Will add elm-tests in a future PR.

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated. See Running tests for more details
• Self-reviewed the diff
• Changelog fragment added in .changes/

[Copilot]

Pull request overview

Adds the first “real” functionality to the cardano-wasm browser demo by wiring Elm UI/state to the cardano-wasm JS wrapper via ports, enabling multi-wallet generation/restoration and network switching with address re-derivation.

Changes:

• Introduce Elm module skeleton (Types/State/Update/View/Wasm/Net/Format/Ports) implementing wallet list UI, console/toast, and modal flows.
• Expand web/ports.js port glue to generate/restore stake wallets and derive addresses for different networks.
• Add Herald changelog fragment for the cardano-wasm demo feature set.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
cardano-wasm/demo/web/ports.js	Implements Elm↔JS port handlers for wallet generation/restoration, address derivation, and clipboard writes.
cardano-wasm/demo/src/Wasm.elm	Encodes outbound port commands and decodes inbound results/errors from JS.
cardano-wasm/demo/src/View.elm	Adds the demo UI: wallets list/cards, restore form, console, modal, and toast.
cardano-wasm/demo/src/Update.elm	Implements TEA update logic for network switching, wallet flows, logging, and copy/toast behavior.
cardano-wasm/demo/src/Types.elm	Defines demo model, wallet/key types, and message/event types.
cardano-wasm/demo/src/State.elm	Provides initial model and pure helpers for wallet management, logging, and toast timer.
cardano-wasm/demo/src/Ports.elm	Declares the raw Elm ports used by the demo.
cardano-wasm/demo/src/Net.elm	Adds static network tables/tags/magic and faucet/explorer URLs.
cardano-wasm/demo/src/Main.elm	Wires Browser.element, subscriptions, and module boundaries together.
cardano-wasm/demo/src/Format.elm	Adds formatting/parsing helpers (ADA/lovelace conversion, shortening, defaults).
.changes/20260718_cardano_wasm_demo_wallets.yml	Declares the demo’s multi-wallet management as a feature for cardano-wasm.