buildlang 1.1.0 - accountable scientific compute

Minor release. A second, independent receipt family beyond the capability
(check) receipts: the scientific-runtime receipt
(buildlang-scientific-runtime-receipt/v0).

• buildc run --emit-receipt <path> --invariant <NAME> runs a numeric .bld
  kernel, checks a stated invariant over its output series, and seals a
  re-checkable JSON receipt. buildc receipt verify RE-RUNS the program and
  re-derives the verdict (typed failure_class, verdict-gated exit codes).
• Six invariants, each a fixed re-checked tolerance with a paired
  positive/negative kernel: energy-monotone, conservation, bounded
  (discrete maximum principle), energy-identity (a quantitative energy-balance
  residual), relation (--columns N, verifier-compared columns), and
  conserved-band (approximate conservation, e.g. a symplectic integrator).
• buildc receipt export emits witnessed measurement rows.

Backward compatible: run without --emit-receipt is byte-identical to 1.0.x.
Honest scope: the receipt witnesses the observed output series, not model
correctness or any physical law (NOT_A_NEW_PHYSICAL_LAW). C stays the only
production-verified backend. Install: cargo install buildlang. Details:
docs/SCIENTIFIC-RECEIPT.md.