feat: introduce prom client metrics

[bosbaber]

Context

We have a problem where are really struggle to understand the reason of performance bottlenecks. This is especially true whenever the wallet appears unexpectedly slow.

This pull request adds Prometheus-compatible HTTP metrics to both the Boutique and Wallet backend services, enabling improved observability and monitoring. It introduces a new metrics server running on a dedicated port, exposes metrics via a /metrics endpoint, and integrates middleware to collect HTTP request metrics. The changes are thoroughly tested and configurable via Helm charts and environment variables.

[Copilot]

Pull request overview

This PR adds Prometheus-compatible HTTP metrics to the Wallet and Boutique backends by introducing a shared metrics registry, HTTP request instrumentation middleware, and a dedicated /metrics server bound on a separate port. This improves observability for performance and bottleneck investigations across the TestNet services.

Changes:

• Added a shared @shared/backend metrics module (registry + HTTP middleware + standalone /metrics server) with Jest coverage.
• Wired metrics registry + HTTP middleware into both Wallet and Boutique backend apps, and started a dedicated metrics server on METRICS_PORT.
• Exposed and configured the metrics port via Helm charts (deployment ports + service ports + configMaps).

Reviewed changes

Copilot reviewed 19 out of 20 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
pnpm-lock.yaml	Adds @prometheus-io/client and new Jest-related deps for shared backend tests.
packages/shared/backend/src/middleware/metrics.ts	Introduces metrics registry, HTTP metrics middleware, and a dedicated /metrics server.
packages/shared/backend/src/middleware/index.ts	Re-exports metrics utilities from the shared backend middleware barrel.
packages/shared/backend/tests/middleware/metrics.test.ts	Adds Jest tests for /metrics endpoint behavior and HTTP middleware labeling.
packages/shared/backend/package.json	Adds prom client dependency; switches shared backend to run Jest tests.
packages/shared/backend/jest.config.json	Adds Jest config for shared backend TypeScript tests.
packages/wallet/backend/src/createContainer.ts	Registers a shared metricsRegistry in the wallet DI container.
packages/wallet/backend/src/config/env.ts	Adds METRICS_PORT env var (default 9464).
packages/wallet/backend/src/app.ts	Starts a metrics server and installs HTTP metrics middleware in wallet backend.
packages/wallet/backend/package.json	Adds @prometheus-io/client dependency to wallet backend.
packages/boutique/backend/src/container.ts	Registers a shared metricsRegistry in the boutique DI container.
packages/boutique/backend/src/config/env.ts	Adds METRICS_PORT env var (default 9464).
packages/boutique/backend/src/app.ts	Starts a metrics server and installs HTTP metrics middleware in boutique backend.
packages/boutique/backend/package.json	Adds @prometheus-io/client dependency to boutique backend.
helm/testnet-wallet/values.yaml	Adds metricsPort, exposes container/service metrics port, and configures METRICS_PORT.
helm/testnet-wallet/tests/services_test.yaml	Validates wallet service includes the metrics port.
helm/testnet-wallet/tests/deployment.backend_test.yaml	Validates wallet deployment exposes the metrics port and sets METRICS_PORT.
helm/testnet-boutique/values.yaml	Adds metricsPort, exposes container/service metrics port, and configures METRICS_PORT.
helm/testnet-boutique/tests/services_test.yaml	Validates boutique service includes the metrics port.
helm/testnet-boutique/tests/deployment.backend_test.yaml	Validates boutique deployment exposes the metrics port and sets METRICS_PORT.

Files not reviewed (1)

• pnpm-lock.yaml: Generated file

Suppressed comments (1)

packages/shared/backend/tests/middleware/metrics.test.ts:49

• server.address() can return null (before the 'listening' event) or a string, so casting it directly to { port: number } can throw at runtime or be flaky. Wait for 'listening' and assert the address type before reading .port.

  it('startMetricsServer 404s on any other path', async (): Promise<void> => {
    const register = createMetricsRegistry()
    const server = startMetricsServer(register, 0)

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