Initialize wiggleverse-ecomm (clean ecomm rebuild)

Greenfield skeleton for the clean ecomm implementation, superseding the R01-R07
reference prototype (wiggleverse-ecomm-prototype). One Name "ecomm"; app.json
wires the code repo, the wiggleverse-ecomm-content collection repo, and the
session-history/ecomm transcript home. No application code yet — architecture is
to be designed in a brainstorming/planning session.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,8 @@
+.DS_Store
+.venv/
+__pycache__/
+*.pyc
+node_modules/
+dist/
+.env
+*.local