Prepare 0.7.0 release notes for recorded geometry viewer changes

[superWorldSavior]

Context

main now contains significant viewer/session changes after the published 0.6.1 release, including:

• exact recorded geometry sessions;
• the compact MCP View v2 surface;
• refactoring to shared MCP View primitives/components;
• continued separation between direct provider results and recorded/canonical Digital Thread geometry presentation.

These are larger than a patch-level documentation correction and materially change the presentation/session surface while preserving the CAD provider's core compute/export contracts.

Proposed release treatment

Prepare the next release as 0.7.0 unless additional contract review shows the changes are strictly patch-compatible and intentionally not user-visible.

Acceptance criteria

• CHANGELOG.md includes an unreleased / 0.7.0 section covering the recorded geometry session model, whole-view ownership, resource transport, and MCP View v2 component refactor in concise user-facing language.
• Release notes distinguish clearly between:
  • direct build123d_execute / build123d_export result rendering;
  • Project geometry review sessions;
  • canonical Digital Thread recorded geometry sessions.
• Documentation reiterates that viewer/session presentation does not turn standalone provider evidence into canonical product admission.
• deno.json, package metadata, viewer manifest/app version, and release tag remain synchronized at release time.
• CI rebuilds the committed viewer bundle from the pinned shared MCP View dependency and remains clean before tagging.
• No accidental breaking change is introduced into the existing io.casys.mcp-build123d.geometry-result/1.0 result envelope without an explicit schema/version decision.