chore(ci): remove un-instantiated e2e.yml (0 jobs, permanently failing) (#19)

This repo`s `.github/workflows/e2e.yml` is an **un-instantiated
scaffold**: `jobs:` is present but every job block is commented out. An
empty `jobs:` map is invalid, so the run dies with **0 jobs** and
`conclusion=failure` — permanently, on every push touching `src/**`,
`ffi/**` or `tests/**`.

It has **never run a single test**, so nothing is lost by removing it.

**Why delete rather than instantiate:** comparing git blob SHAs against
a known-pure template clone shows this repo`s `src/` is the RSR
scaffold, differing in at most 4 files (largely just the repo name).
There is no project-specific behaviour here to exercise end-to-end yet,
and a job written anyway would pass without testing anything — a fake
gate.

**Debt recorded, not hidden:** this repo has **no E2E coverage**. When
real code lands, add a genuine E2E job and prove it can fail. The
scaffold remains available in the template repo.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

Author: hyperpolymath