Two delegated_access examples (mcp-fastmcp and mcp) were both named
delegated-access-example, causing uv workspace member name collision.

Renamed to delegated-access-fastmcp-example and
delegated-access-lowlevel-example.

Package-level [tool.uv.sources] with `workspace = true` caused failures
when examples resolved deps via editable paths — uv loaded the package
pyproject outside the workspace context and could not resolve the
workspace references.

The root pyproject.toml already declares all workspace sources, so
package-level declarations were redundant. Removing them lets examples
run directly from their directory with `uv run python main.py`.

…er README

Incorporates improvements from Sean's PR #94:
- Support KEYCARD_ZONE_URL in addition to KEYCARD_ZONE_ID
- Remove hardcoded fallback values for credentials
- Streamline README install/run steps
- Add note for local SDK development workflow

The workspace fix makes examples resolve against local source by
default — no need for a separate root-level command.

The test suite imports the example without env vars set. Removing the
fallback defaults caused ClientSecret to receive None, failing the
client_id validation.

Sean's improvement removed the explicit zone_id parameter, relying on
AuthProvider's internal env var discovery. But the test suite imports the
example without env vars, so AuthProvider raises
AuthProviderConfigurationError. Restore the fallback default.