README: retire the legacy headline benchmark table in favour of the generated tests/reports #36

Summary

The README top table still carries numbers from before numeric_vm replaced the name-based fib/numericLoop intercepts (CLI Process Cold Start 2.000 ms (24.6x Node), Compute (Fib40 + 10M Loop) 1.924 ms, 1,000-Tenant MicroVM Swarm 2.62 ms). Those are no longer produced by the current code path and differ from the project's own generated report in tests/reports/latest.md.

Proposal

• Replace the README headline table with an excerpt of (or link to) tests/reports/latest.md so there is one source of truth that regenerates with the harness.
• State runtime versions in every table. latest.md currently compares against Node v27.0.0-alpha; adding a Node LTS column alongside it would pre-empt the obvious "why alpha?" question from readers, regardless of which is faster.
• Add a short note in the benchmarks chapter that numeric_vm detects f(n-1)+f(n-2) recurrences structurally and lowers them to an O(N) loop, so fib(40) timings are understood as an optimisation result rather than naive execution.