feat(ui): frontend mock mode for offline dev

[schronck]

What

Adds a dev-only mock mode to the frontend so the UI can run with realistic data without a Canton node or Keycloak.

cd frontend
npm run dev:mock        # = MOCK=true vite  →  http://localhost:5173

How

• A small Vite plugin (vite.config.ts, apply: 'serve') intercepts the backend REST routes and serves JSON from frontend/mocks/*.json. It is never included in production builds.
• Path → fixture: /governance/state → governance_state.json, with a longest-prefix fallback.
• party_id-aware: a request with ?party_id=<prefix>::… prefers a <base>__<prefix>.json override before the generic file — so governance state/confirmations can differ per party (e.g. gov core deployed on some parties, not others) without duplicate cards.
• Unmapped GETs return {}, unmapped POSTs return {"status":"completed"} (treated as success by the UI).

Fixtures (frontend/mocks/)

Realistic devnet-flavoured data covering every screen and dialog:

• 18 decentralized parties (scattered thresholds/owners/participants, mixed auth states), 14 peers with real FQDN addresses and an online/offline split, 18 packages with peer-compare drift.
• Pending approvals: 12 workflow runs across in-progress/completed/failed/cancelled, 5 invitations, and per-party governance confirmations.
• Gov core deployed on 4 authed parties (per-party state + confirmations); the rest show "Deploy contracts".
• Party detail endpoints (holdings, instruments, vaults, audit trail, transfer-factories, party-config, known-members, auth/test, …) so opening a party renders cleanly.

Verified

Clicked through all tabs, party detail, and every dialog (New Proposal + 26 types, Governance Actions, Deploy Contracts, peer-compare matrix, DAR upload/distribute, party config, Test Auth) — zero console/page errors. Production npm run build unaffected.

To change the data, edit frontend/mocks/*.json — the page hot-reloads.

[Copilot]

Pull request overview

Adds a dev-only “mock mode” for the frontend so the UI can be developed and demoed offline (no Canton node / Keycloak), by serving API responses from JSON fixtures via a Vite dev-server middleware.

Changes:

• Introduces a mock-api Vite plugin (serve-only) that intercepts known REST route prefixes and serves frontend/mocks/*.json fixtures with longest-prefix fallback + optional party_id overrides.
• Adds npm run dev:mock to start Vite with MOCK=true.
• Adds a comprehensive set of mock JSON fixtures covering most UI screens/dialogs.

Reviewed changes

Copilot reviewed 42 out of 42 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
frontend/vite.config.ts	Adds a dev-only Vite middleware plugin to serve API fixtures from frontend/mocks/ when MOCK=true.
frontend/package.json	Adds dev:mock script to enable mock mode.
frontend/mocks/auth-config.json	Mock response for /auth-config.
frontend/mocks/auth_status.json	Mock response for /auth/status.
frontend/mocks/auth_test.json	Mock response for /auth/test.
frontend/mocks/contracts_query.json	Mock response for /contracts/query.
frontend/mocks/credential-offers.json	Mock response for /credential-offers.
frontend/mocks/decentralized-parties.json	Mock response for /decentralized-parties (party list + metadata).
frontend/mocks/governance_burn-requests.json	Mock response for /governance/burn-requests.
frontend/mocks/governance_chain-audit.json	Mock response for /governance/chain-audit.
frontend/mocks/governance_confirmations.json	Default mock response for /governance/confirmations.
frontend/mocks/governance_confirmations__cbtc-network.json	Party-scoped override fixture for /governance/confirmations?party_id=cbtc-network::….
frontend/mocks/governance_confirmations__governance-core.json	Party-scoped override fixture for /governance/confirmations?party_id=governance-core::….
frontend/mocks/governance_confirmations__ibtc-admin.json	Party-scoped override fixture for /governance/confirmations?party_id=ibtc-admin::….
frontend/mocks/governance_known-members.json	Mock response for /governance/known-members.
frontend/mocks/governance_mint-requests.json	Mock response for /governance/mint-requests.
frontend/mocks/governance_state.json	Default mock response for /governance/state.
frontend/mocks/governance_state__cbtc-mint-authority.json	Party-scoped override fixture for /governance/state?party_id=cbtc-mint-authority::….
frontend/mocks/governance_state__cbtc-network.json	Party-scoped override fixture for /governance/state?party_id=cbtc-network::….
frontend/mocks/governance_state__governance-core.json	Party-scoped override fixture for /governance/state?party_id=governance-core::….
frontend/mocks/governance_state__ibtc-admin.json	Party-scoped override fixture for /governance/state?party_id=ibtc-admin::….
frontend/mocks/governance_transfer-instructions.json	Mock response for /governance/transfer-instructions.
frontend/mocks/holdings.json	Mock response for /holdings.
frontend/mocks/instruments.json	Mock response for /instruments.
frontend/mocks/invitations.json	Mock response for /invitations.
frontend/mocks/keys_status.json	Mock response for /keys/status.
frontend/mocks/network-config.json	Mock response for /network-config.
frontend/mocks/network-info.json	Mock response for /network-info.
frontend/mocks/node-config.json	Mock response for /node-config.
frontend/mocks/operator-info.json	Mock response for /operator-info.
frontend/mocks/packages.json	Mock response for /packages.
frontend/mocks/packages_compare-peers.json	Mock response for /packages/compare-peers.
frontend/mocks/packages_vetted.json	Mock response for /packages/vetted.
frontend/mocks/participants-status.json	Mock response for /participants-status.
frontend/mocks/party-config.json	Mock response for /party-config (and fallback for /party-config/<id>).
frontend/mocks/services_provider.json	Mock response for /services/provider.
frontend/mocks/services_user.json	Mock response for /services/user.
frontend/mocks/token-standard-contracts.json	Mock response for /token-standard-contracts.
frontend/mocks/transfer-factories.json	Mock response for /transfer-factories.
frontend/mocks/transfer-preapprovals.json	Mock response for /transfer-preapprovals.
frontend/mocks/vaults.json	Mock response for /vaults.
frontend/mocks/workflows.json	Mock response for /workflows.

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[schronck]

Folded into #212 — consolidating the UI modernization into a single PR. These commits are already included in #212.