add chat_as_soul handler for multi-soul rooms

Routes a new event_type "chat_as_soul" through dharma/recv. The Studio
preassembles the system_prompt + transcript and dispatches per-speaker;
the soul-binary just performs the LLM call as the requested speaker_slug.
No engram_compile here — each soul has its own engram (88xx) and the
Studio queries it before composing the prompt.

Also: track the previously-untracked split source modules (chat, routes,
memory, awareness, studio) and add build.sh so the binary can be rebuilt
without the studio’s concat trick. elb resolves the import graph and
emits one .c per .el; we link them together with cc. dist/soul-el now
points at dist/neuron via symlink (matching the launchctl plist).

routes.elh

@@ -0,0 +1,11 @@
+// auto-generated by elc --emit-header - do not edit
+extern fn strip_query(path: String) -> String
+extern fn err_404(path: String) -> String
+extern fn err_405(method: String, path: String) -> String
+extern fn route_health() -> String
+extern fn route_lineage() -> String
+extern fn route_imprint_contextual(body: String) -> String
+extern fn route_imprint_user(body: String) -> String
+extern fn route_synthesize(body: String) -> String
+extern fn handle_dharma_recv(body: String) -> String
+extern fn handle_request(method: String, path: String, body: String) -> String