feat(flows): lanes as a tinyflows graph, specialised reviewers, and sub-agents with tools

.gitmodules

@@ -1,3 +1,6 @@
 [submodule "vendor/tinyagents"]
 	path = vendor/tinyagents
 	url = https://github.com/tinyhumansai/tinyagents.git
+[submodule "vendor/tinyflows"]
+	path = vendor/tinyflows
+	url = https://github.com/tinyhumansai/tinyflows.git

AGENTS.md

@@ -20,6 +20,9 @@
   is a new folder, never a new module.
 - `vendor/tinyagents` — the agent harness, as a git submodule. Never edit it
   here; change it upstream and bump the pin.
+- `vendor/tinyflows` — the orchestration graph, as a git submodule. Same rule.
+  Lane concurrency, the consensus panel and sub-agents are all expressed as
+  graphs against it; see `docs/modules/flows/README.md`.
 - `docs/modules/<module>/README.md` — one document per `src/` module.
 - `examples/` — declared explicitly in `Cargo.toml` with `required-features`, so
   credential-needing smoke tests never build in CI.