Repoint microReticulum submodule at torlando-tech/pyxis-fixes-on-0.3.0

Was: attermann/microReticulum @ tag 0.3.0 (vanilla)
Now: torlando-tech/microReticulum @ pyxis-fixes-on-0.3.0 @ 97e72a3
     = vanilla 0.3.0 + 3 focused upstream-PR-ready commits

The branch carries our spec-conformance fixes that vanilla upstream
0.3.0 is missing:

  bb177e4  Fix PKCS7 padding to be spec-conformant (RFC 5652 §6.3)
  918f743  Fix HMAC convenience digest() helper hashing the message twice
  97e72a3  Apply RFC 7748 §5 scalar clamping in X25519PrivateKey constructor

Each is one self-contained commit with a unit test that catches the
bug — designed so they can be cherry-picked or PR'd to attermann
upstream individually after we've finished e2e testing pyxis on top.

The conformance bridge baseline against vanilla 0.3.0 was 50/85;
expectation post-this-pin is to recover to 52/85 (the X25519 clamping
unblocks both x25519_generate and identity_from_private_key).

.gitmodules

@@ -1,6 +1,10 @@
 [submodule "deps/microReticulum"]
 	path = deps/microReticulum
-	url = https://github.com/attermann/microReticulum.git
-	# Pinned at the 0.3.0 release tag so the build is reproducible. Bump
-	# the pin deliberately when we want a newer microReticulum (and re-run
-	# the conformance suite to catch any drift).
+	url = https://github.com/torlando-tech/microReticulum.git
+	branch = pyxis-fixes-on-0.3.0
+	# torlando-tech/microReticulum's pyxis-fixes-on-0.3.0 = upstream
+	# attermann/microReticulum @ 0.3.0 + a small focused commit series of
+	# interop fixes (PKCS7 spec-correct padding, HMAC double-update,
+	# X25519 RFC 7748 scalar clamping). Each commit is upstream-PR-ready;
+	# the branch will roll forward as new fixes are surfaced and fold
+	# back into upstream once the PRs land.