archetypes: build an archetype agent from its archetype's module on the hive

The hive reads the agent-archetype key when it provisions and rebuilds an
agent and keeps it in swarm-agent-archetypes.json. For an archetype agent
the meta flake has no agent-<name> input and mkAgent imports
hyperhive.hyperhiveArchetypes.<name>.module; provisioning, rebuilds, the
meta-input cascade, a deploy's rev and the startup migration skip the
config repos. The harness gets HIVE_ARCHETYPE and the system prompt says
the agent has no config repo. The create form sends the picked archetype.
Adds the android-dev built-in.

Refs #5386

docs/agent-lifecycle/agent-roster.md

@@ -106,13 +106,16 @@ state dirs work as for every other agent.
   deploy log). Any agent holding it gets the same mounts.
   The operator dashboard's `POST /api/meta-update` is the only path
   that writes `flake.lock`.
-- **Prompt** — identical for every container: `prompts/system.md`
+- **Prompt** — identical for every container but one block (below):
+  `prompts/system.md`
   carries `<!-- role:agent -->` / `<!-- role:manager -->` marker
   blocks, and `prompt::render` filters for `"agent"` unconditionally,
   manager included ("always `agent` role — there is only one role",
   `hive-agent/src/prompt.rs`'s own module doc). The `role:manager`
   blocks are dead in production, exercised only by a unit test
-  (`filter_role_blocks(SAMPLE, "manager")`).
+  (`filter_blocks(SAMPLE, "role", "manager")`). The one block that differs
+  is `<!-- config:repo -->` vs `<!-- config:archetype -->`: an agent built
+  from an [archetype](../swarm/archetypes.md) is told it has no config repo.
 - **Tool allow-list** — the MCP tools claude sees come from the agent's
   permissions alone, the same mechanism for every agent
   ([`docs/turn-loop/mcp.md`](../turn-loop/mcp.md)). Ruth's permissions