Cardano Updates

- express ^5.2.1, body-parser ^2.3.0, express-prom-bundle ^8, prom-client ^15,
  @types/express ^5 (cardano-services); express ^5 (cardano-services-client devDep)
- HttpServer.ts: assert express-prom-bundle v8 Opts (summary|histogram union) shape
- HttpServer.test.ts: body-parser v2 leaves bodyless req.body undefined (was {})
- util/http.ts: express 5's app.listen forwards bind errors to the listen callback
  (error-first) rather than only the 'error' event; make listenPromise reject on a
  failed bind for both express apps and raw http.Server (otherwise EADDRINUSE would
  silently resolve with an unbound server)

Collapses the express-4 stack onto the modern 2.x line. All routes static;
32/32 HttpServer + http-util tests pass.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

Native Yarn dedupe over the full merged set (wdio v9 + resolutions +
express 5), collapsing ~192 redundant same-major duplicate copies
(411 -> 338 multi-version packages).

@scure/base is left split deliberately: deduping core's `^1.1.1` (1.1.7)
up to the `~1.1.6` line (1.1.9) tightens bech32.decode's parameter type
to `${string}1${string}`, which core's branded-string callers don't
satisfy -> breaks the build. Adopting the stricter types is a separate
change. Validated with a clean (no tsbuildinfo) full build.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

* mithril-aggregator-client from `0.2.2` to `0.2.3`
* mithril-aggregator-discovery from `0.1.8` to `0.1.9`
* mithril-protocol-config from `0.1.9` to `0.1.10`
* mithril-aggregator from `0.9.9` to `0.9.10`
* mithril-client-cli from `0.13.16` to `0.13.17`
* mithril-common from `0.7.7` to `0.7.8`
* mithril-end-to-end from `0.5.1` to `0.5.2`
* openapi.yaml from `0.1.66` to `0.1.67`

- remove `Message` suffix from `DiscontinuedSignedEntityType` enums
- avoid magic strings in discriminant message `From<&str>` impl
- doc: clarify that `Unknown` variant serialize as `null` for JSON
- doc: simplify some comments
- test: cover discriminants `From<&str>`
- test: simplify redundant display tests
- test: simplify json roundtrips tests by using an helper method