Release v0.1.6 with pinned Nim dependency metadata for downstream builds

[Copilot]

Downstream builds were resolving enkodo@0.1.5, which did not enforce the dependency constraints needed by current consumers and led to a compile failure (undeclared identifier: crypto_key_exchange). This PR publishes a new package version carrying the pinned dependency metadata and aligns docs to that release.

• Package release metadata

  • Bumped /enkodo.nimble version from 0.1.5 to 0.1.6 so dependents can resolve a release with explicit dependency pins.
  • Keeps dependency constraints explicit in package metadata (flatty == 0.3.4, monocypher == 0.2.1) for deterministic resolution.

• Documentation alignment

  • Updated README Deno import example to reference v0.1.6 instead of v0.1.5.

# enkodo.nimble
version = "0.1.6"
requires "flatty == 0.3.4"
requires "monocypher == 0.2.1"

[hortinstein]

@claude can you ensure that monocypher == 0.2.1