Initial commit: data-server leaf crate extracted from myc

High-performance, thread-safe loader and cache for binary market data
files (M1/tick). No dependency on the rest of myc; only chrono, regex, zip.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,5 @@
+/target
+
+# This crate is a library: do not commit the lockfile.
+# Consumers pin exact versions in their own Cargo.lock.
+Cargo.lock