chore(vs-extension): remove dev-only files from repo and VSIX

Audit of the develop->main integration surfaced stray files that were
never meant to ship:

- packages/b2c-vs-extension/.claude/settings.json — a contributor's local
  Claude permission settings (hardcoded a personal home path) that was
  being packaged into the published VSIX. Removed and .claude/ added to
  the extension .gitignore.
- DEVELOP-TESTING-SUMMARY.md — a scratch 'features to test' note at the
  repo root, not product documentation. Removed.
- test-workspace/** — manual dev fixtures (not used by automated tests)
  were bundling into the VSIX. Excluded via .vscodeignore.

No functional change; only affects what lands in the repo and the
packaged extension.

Author: clavery

.changeset/vsix-packaging-cleanup.md

@@ -0,0 +1,5 @@
+---
+'b2c-vs-extension': patch
+---
+
+Stop bundling development-only files into the published extension. The packaged VSIX no longer includes the `test-workspace/` sample cartridges or local `.claude/` editor settings, reducing package size and removing files that were never meant to ship.

DEVELOP-TESTING-SUMMARY.md

@@ -1,6 +1,7 @@
 out
 dist
 node_modules
+.claude/
 .vscode-test/
 .vsce-stage/
 *.vsix

packages/b2c-vs-extension/.claude/settings.json

@@ -1,5 +1,7 @@
 .vscode/**
 .vscode-test/**
+.claude/**
+test-workspace/**
 src/**
 !src/webview.html
 !src/api-browser/swagger-webview.html