Update Base Demo references for Base Foundry org migration

[codeforester]

Context

base-demo moved to basefoundry/base-demo, but current docs and installer paths still point at codeforester GitHub coordinates. Some codeforester strings are Java package names or existing module identifiers and should not be swept blindly.

Scope

• Update README clone links and related repo links to basefoundry/base, basefoundry/base-demo, and basefoundry/banyanlabs.
• Update install.sh defaults for PROJECT_REPO_URL and BASE_INSTALL_URL.
• Update GitHub workflow references that clone Base from codeforester/base.
• Review Go module path github.com/codeforester/base-demo/services/go-api and decide whether to move it to github.com/basefoundry/base-demo/services/go-api as part of this PR.
• Leave Java package names such as com.codeforester.basedemo unchanged unless there is a separate namespace decision.

Validation

• rg -n "github.com/codeforester|codeforester/base|codeforester/base-demo|codeforester/banyanlabs" README.md install.sh .github services docs tests and review any remaining hits as intentional.
• ./tests/validate.sh
• git diff --check