refresh: bump to v0.6.15 + PPL ratio surfaced (2026-05-19)

README.md

@@ -20,11 +20,9 @@ pinned: false
 
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-## v0.6.9 shipped 2026-05-15 — security release + new Mistral 7B record
+## v0.6.15 current — minimal clean release
 
-`pip install --upgrade ultracompress` — RCE-class fix on `torch.load()` paths + MANIFEST-scrubbed sdist. v0.6.7 + v0.6.8 yanked from PyPI. Drop-in replacement, no code changes required.
-
-**Mistral-7B-v0.3 hits 1.00548×** — a strong dense 7B-class lossless 5-bit result.
+Only `pip install ultracompress` (v0.6.15) is on PyPI. The package is the minimal SHA-256 verifier; codec internals are patent-protected and not shipped in the public package. Prior dev releases were retired during the 2026-05-18 cleanup. Mistral-7B-v0.3 hits 1.00548× — a strong dense 7B-class lossless 5-bit result.
 
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