Fix bit(1) import coercion and subpath login redirect; add GitHub export script

Loader: bool() on pymysql bit(1) bytes is always true - isinstallable
and isshopfloor imported as 1 for every row; route through _truthy_bit.
The employee source DB is now optional (shopdb-only imports).

Frontend: under a subpath mount the 401 interceptor stored the browser
path (mount base included) as the login redirect and the router applied
its base again (/ops/ops). New stripBase() keeps redirects base-free.

tools/export-github.sh automates the publication flow: prune + scrub +
commit into ~/projects/shopdb-flask-pub and emit a transfer bundle.

README.md

@@ -108,7 +108,7 @@ SQLite). Do not run dev or production against SQLite.
 
 ### Distribution
 
-The application is distributed internally through the GE Aerospace Gitea. Clone
+The application is distributed through the internal GE Aerospace git server. Clone
 it from there; there is no public package or image registry.
 
 ### Fast path (Docker)