Cardano Updates

* uplc-evaluator: bound service teardown, add timeout safety net

Test teardown ran terminateProcess followed by an unbounded
waitForProcess, so a spawned service that missed SIGTERM hung the run
until the 2h CI cap (plutus-private#2257). Bound the wait and escalate to
SIGKILL, add a per-test tasty timeout as a safety net, and a regression
test that drives a SIGTERM-ignoring process.

* uplc-evaluator: drop integration tests from the per-PR required gate

The uplc-evaluator is a non-critical on-demand tool, so its integration
tests need not gate every PR. The test executable is still built on every
PR; the suite is run nightly instead. See plutus-private#2257.

* nightly: run uplc-evaluator integration tests

See plutus-private#2257.

* address copilot review on PR #7817

- plutus-benchmark/uplc-evaluator/test/Harness.hs:126 — re-check getProcessExitCode before SIGKILL escalation (https://github.com/IntersectMBO/plutus/pull/7817#discussion_r3414323806)

Move the per-PR opt-out of the uplc-evaluator integration tests from a post-hoc removeAttrs in outputs.nix to doCheck = false on the test component in project.nix, so the check is never generated rather than filtered out after the fact. The test executable is still built on every PR and the suite still runs nightly.

Trim verbose teardown comments and drop issue-tracker references from public source.

* Increase lower bound on aeson >= 2.3 to avoid a DoS vulnerability in
  earlier versions:
    https://haskell.github.io/security-advisories/advisory/HSEC-2026-0007.html
* Make it compatible with QuickCheck == 2.18.* and earlier.

* Increase lower bound on aeson >= 2.3 to avoid a DoS vulnerability in
  earlier versions:
    https://haskell.github.io/security-advisories/advisory/HSEC-2026-0007.html
* Make it compatible with QuickCheck == 2.18.* and earlier.

* Increase lower bound on aeson >= 2.3 to avoid a DoS vulnerability in
  earlier versions:
    https://haskell.github.io/security-advisories/advisory/HSEC-2026-0007.html
* Make it compatible with QuickCheck == 2.18.* and earlier.

No code change. The previous run was fully green except a flaky failure in
plutus-benchmark's uplc-evaluator-integration-tests, whose evaluator service
exited with code -15 (SIGTERM) — unrelated to this PR.

Co-Authored-By: Claude Opus 4.8 <[email protected]>