26.7.0

Release 26.7.0 — engine bump to 26.6.0 + shared error formatter

What changed

• Bumped the MCP package version GroupDocs.Signature.Mcp 26.5.0 → 26.7.0 (CalVer).
• Bumped the engine GroupDocs.Signature 26.2.0 → 26.6.0 (latest stable on NuGet;
  a four-minor jump). No public API drift affecting the tool surface — Sign,
  Verify, all five Search* tools, and GetDocumentInfo compile and behave
  unchanged against 26.6.0.
• Extracted the per-tool private FormatException helpers (duplicated across all
  eight tools) into a single shared Tools/ToolError.cs
  (ToolError.Format(op, file, ex, subjectSuffix = null)). Every tool's catch
  now calls it. Output text is byte-for-byte identical to the previous per-tool
  helpers — the failure prefixes (Signing failed for, Verification failed for,
  Barcode search failed for, Document-info lookup failed for, etc.) are
  preserved, so integration tests that match on the prefix are unaffected.
  Sign and Verify pass their (type: '<type>') subject via the new
  subjectSuffix parameter.

Why

Routine maintenance release: pick up the latest stable engine and consolidate the
duplicated error-formatting boilerplate (8 identical copies) into one shared helper
per the cross-product MCP conventions (shared ToolError supersedes per-class
FormatException once ≥3 tools exist).

Migration / impact

• No behavioural change to any tool's success or failure output.
• Engine transitive note: as of 26.6.0 the resolved GroupDocs.Signature.Net80
  runtime package now declares SkiaSharp 3.119.0 +
  SkiaSharp.NativeAssets.Linux.NoDependencies 3.119.0 transitively (it did not at
  clone time). The MCP still does not pin SkiaSharp manually — the native
  libSkiaSharp now arrives transitively (Pitfall S). The existing
  System.Security.Cryptography.Pkcs 9.0.0 override remains in place.

Full Changelog: 26.5.0...26.7.0