Cleaned the concurrent session's half-rebrand inconsistency (166 files):
- pip/pypi refs hanzoflow -> hanzo-flow (matches hanzo-flow-base/sdk)
- module paths/commands/devcontainer hanzoflow -> flow (the import name + CLI)
- env vars HANZOFLOW_ -> FLOW_ (was inconsistent with the LANGFLOW_->FLOW_ sweep)
- fixed a stale src/backend/base/hanzoflow/ path that didn't exist
- product display HanzoFlow -> 'Hanzo Flow' in docs; kept HanzoFlow only as a
code identifier where a space is illegal
Canonical: pip install hanzo-flow / import flow / `flow` CLI. compileall clean.