v0.1.0 — initial env decoder

[0.1.0] - 2026-04-24

Initial release. Extracted from produktor.io/ai-fabric/pkg/env per
inventar/docs/asr/ASR-0008-ai-fabric-audit.md.

Added

• Unmarshal(dst, opts...) — decode all process env vars into a Go struct.
• UnmarshalPrefix(dst, prefix, opts...) — prefix-scoped variant that
  strips the prefix before building the path.
• AsMap() / AsMapPrefix(prefix) — escape hatch returning the nested
  map[string]any built from os.Environ().
• Options: WithTrim, WithWeaklyTyped, WithTagName, WithDecodeHook.
• TrimSpace on string values is enabled by default; disable with
  WithTrim(false).
• Error wrapping with %w on both decoder configuration and decode
  failures — matches markets-platform/TP-general-code/pkg/system
  behaviour, improves on the original ai-fabric version.

Tests

• 15 pure-Go unit tests. No mocks. asMapFromEnviron is tested with
  synthetic environ slices (not a mock — a pure input). Follows the
  eSlider go-* no-synthetic-mocks policy.