Add library build, local cluster script, and example client

Introduce a Makefile that builds libtoastyfs.a and libtoastyfs.so from the
client-side sources (client, tcp, byte_queue, message, basic) so external
programs can link against the ToastyFS client API in include/toastyfs.h.

Add cluster.sh, a convenience script that manages a local 3-node cluster
by spawning toastyfs server processes on ports 8081-8083.  Sub-commands:
up, down, status, logs, and "run <source.c>" which builds the library,
compiles the source against it, starts the cluster, runs the binary, and
tears everything down.

Add examples/example.c demonstrating synchronous PUT, GET, DELETE, and a
NOT_FOUND verification.

Fix a stack overflow in the MAIN_SERVER entry point: ServerState is ~40 MB
(MetaStore holds 4096 ObjectMeta entries) and was declared on the stack.
Heap-allocate it instead.

https://claude.ai/code/session_019DVhmc25jfzcHnmdNxzib2

.gitignore

@@ -6,4 +6,9 @@ toastyfs_simulation
 *.gcov
 *.info
 coverage_html/
-*.log
+*.log
+*.o
+*.a
+*.so
+examples/example
+.cluster/