edge-bench-rs: a library for the worker; rules from the lease; the wire format

- src/lib.rs: the indexing modules as a library, for edge-bench-rs and
  the coming edge-node worker.
- Rules as a lease brings them (priorities, dropped signatures and
  tools, per-article parts, sample share, executables) instead of
  DEFAULT_RULES hard-coded; RangeIndexer takes them and a resume point.
- Fragments carry everything the TypeScript Fragment has (poster,
  subject, groups, release): the server stores them for the merger.
- wire.rs: a batch as toWire makes it (camelCase JSON, payloads in
  base64). edge-bench-rs --wire writes it; check.ts --wire compares it
  with toWire of the TypeScript batch: identical on models-a and
  ath-2013.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tools/edge-bench-rs/Cargo.toml

@@ -14,7 +14,11 @@ memchr = "2.8.3"
 mimalloc = "0.1.52"
 regex = "1"
 rustc-hash = "2"
+serde = { version = "1.0.229", features = ["derive"] }
+serde_json = "1.0.151"
 sha1 = "0.10"
+signal-hook = "0.4.5"
+ureq = "3.4.2"
 zstd = "0.13"
 
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