refactor(crypto): implement argon2id in-tree, drop conan-odr-index

[andiwand]

🤖 Generated with Claude Code

argon2/20190702-odr was the last recipe this repo pulled from conan-odr-index. It only existed because upstream's Makefile cannot cross-compile for Android, and ConanCenter declined to carry the fix — upstream has been unmaintained since 2021, so the patch would never go away. (Proposed upstream anyway: P-H-C/phc-winner-argon2#392.)

We use exactly one function of it, so this implements Argon2id in crypto_argon2.* (~300 lines) on top of Crypto++'s BLAKE2b instead of taking on another dependency:

• Crypto++ has no Argon2 and has had no release since 8.9.0 (2023)
• libsodium hardcodes p=1; LibreOffice writes p=4
• Botan and OpenSSL both work but mean a second full crypto library

util::argon2id keeps its signature, so nothing above crypto/ changes. Bad parameters now throw std::invalid_argument instead of silently returning zeros, which is what argon2id_hash_raw's ignored return code used to do.

With that gone, everything resolves from ConanCenter, so the second commit drops the conan-odr-index submodule: no more checkout/export steps in the six workflows that had them, and the conan cache keys lose the submodule sha. The index itself stays where it is — other repos still use it, and its odrcore recipe still serves released 5.x.

Verification

• The reference implementation's published Argon2id vectors, plus vectors generated from it for the multi-lane cases it does not publish — including LibreOffice's t=3, m=65536, p=4.
• 400 randomised cross-checks against the reference implementation (lanes 1–8, iterations 1–5, memory spanning the rounding boundary, tags 4–303 bytes, random passwords and salts): all identical.
• conan graph info . --lockfile conan.lock resolves from a clean conan home with only conancenter, for both the default and the android-armv8 host profile.

Sequential lanes, so no threading: ~66 ms vs ~28 ms for LibreOffice's parameters, once per document open.