ci: add accessibility, Node compatibility, mutation and reproducibility checks

[akindoyinabraham0-collab]

Summary

Add four CI checks that expose accessibility regressions, listener runtime
incompatibilities, weaknesses in event-processing assertions, and contract build
nondeterminism.

• Run the dashboard's shared-component accessibility suite and new real-page
  search, pagination, empty/error recovery, export, and keyboard-dialog flows.
  Publish axe diagnostics in JSON/text artifacts and document required manual
  keyboard, screen-reader, contrast, zoom, and mobile review. Correct the search
  pagination wrapper's ARIA role and two existing Jest setup blockers.
• Declare listener support for Node.js 22.x and 24.x. Independently install,
  build, and run focused pipeline tests on both; exercise emitted lease JavaScript
  and real SQLite/Express/fetch runtime dependencies. Preserve runtime versions
  and failure logs. Align the stale TypeScript lock entry with the manifest using
  official npm registry metadata, without installing dependencies.
• Add eleven deterministic, independently applied mutations across normalization,
  event filtering, and deduplication claim/completion/reorg decisions. Require a
  passing baseline, distinguish infrastructure errors from detected defects, fail
  on survivors, and publish the curated mutation score and per-defect diagnostics.
  Use the existing locked Jest/SWC dependencies, with no new mutation packages.
• Pin Rust 1.90.0 and compare raw release Wasm from two clean Ubuntu jobs using
  separate source paths, Cargo homes, and output directories. Normalize build
  paths, record toolchain/environment/lock metadata, and publish hashes and byte
  differences. Document excluded artifacts and the limits of the comparison.

Validation

• Read-only source, configuration, import, fixture, and diff review completed.
• git diff --check completed with no whitespace errors.
• No application code, tests, builds, mutation runs, package installs, or contract
  compilation were executed locally, as explicitly requested in task.txt.
• CI must establish initial accessibility, compatibility, mutation, and binary
  reproducibility results; no green-run or mutation-score claim is made here.

Scope and existing limitations

The accessibility suite covers representative pages and shared components, not
every dashboard route or a deployed browser session. Runtime smoke tests cover
selected emitted code and real dependencies, not production startup or live
Stellar RPC. Static inspection found pre-existing listener build concerns,
including a duplicate EventDeduplicationService import in src/index.ts and
imports of the Stellar SDK without a declared production dependency. The full
build remains a required check and will report such failures. Contract compilation
must succeed before reproducibility can be established. Mutation scores apply
only to the documented eleven-defect catalog; SQL decisions use a database double.

Closes #1042
Closes #1043
Closes #1040
Closes #1038

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