Move thalamus subcrate into main crate

Move thalamus/ (poc-daemon) source files into src/thalamus/ as a
module of the main crate. The daemon entry point becomes a library
function thalamus::run() with a thin poc-daemon binary for backward
compatibility.

- Copy thalamus source into src/thalamus/, fix crate:: -> super::
- Copy daemon.capnp into schema/, add to build.rs
- Re-export daemon_capnp at crate root (capnp codegen requires it)
- Add thalamus dependencies (capnp-rpc, tokio-util, toml, rustls, etc.)
- Keep thalamus/ subcrate for comparison

Co-Authored-By: Proof of Concept <poc@bcachefs.org>

Cargo.toml

@@ -56,6 +56,15 @@ log = "0.4"
 ratatui = { version = "0.30", features = ["unstable-rendered-line-info"] }
 skillratings = "0.28"
 crossterm = { version = "0.29", features = ["event-stream"] }
+capnp-rpc = "0.20"
+tokio-util = { version = "0.7", features = ["compat"] }
+toml = "0.8"
+tokio-rustls = "0.26"
+rustls = { version = "0.23", default-features = false, features = ["ring", "logging", "std", "tls12"] }
+webpki-roots = "1"
+tracing = "0.1"
+tracing-subscriber = { version = "0.3", features = ["env-filter"] }
+tracing-appender = "0.2"
 
 [build-dependencies]
 capnpc = "0.20"
@@ -91,3 +100,7 @@ path = "src/bin/find-deleted.rs"
 [[bin]]
 name = "consciousness"
 path = "src/bin/consciousness.rs"
+
+[[bin]]
+name = "poc-daemon"
+path = "src/bin/poc-daemon.rs"