bug: upstream command not wired into CLI #224

Bug

Running squad upstream returns Unknown command: upstream even though the implementation exists.

Root Cause

packages/squad-cli/src/cli/commands/upstream.ts is fully implemented (247 lines, 4 subcommands: add/remove/list/sync) with complete docs at docs/features/upstream-inheritance.md, but it was never registered in packages/squad-cli/src/cli-entry.ts.

The if (cmd === 'upstream') routing block is missing from cli-entry.ts, so the command falls through to the 'Unknown command' handler.

Fix

Add routing + help text to cli-entry.ts (9 lines).