RSA: no test vectors with non-byte-aligned moduli

Every RSA key in `testvectors_v1` has a modulus whose bit length is a multiple of 8. I checked all 83 `rsa_*.json` files at the current head (dac1dd4), 629 keyed groups. Bit lengths are exactly 2048, 3072, 4096, or 8192, and the top byte is always at least 0x80.

RFC 8017 permits any modulus bit length, and for a verifier the modulus is attacker-supplied input. It arrives in certificates and presented keys, so a verifier does not get to assume alignment. PSS treats the bit length asymmetrically (`emBits = modBits − 1`), and misalignment exercises two paths that byte-aligned keys never touch:

- **modBits ≢ 1 (mod 8)**, for example 2047: `emLen` still equals the key size, but the zero-bits window in EMSA-PSS-VERIFY steps 6 and 9 widens beyond one bit. Each unchecked top bit doubles a forger's freedom in `maskedDB`. This is the failure family BERserk-style bugs live in.
- **modBits ≡ 1 (mod 8)**, for example 2041: `emBits` is byte-aligned, so `emLen = k − 1`. The encoded message is one octet shorter than the signature, the leftmost-octet-must-be-zero path in RSASSA-PSS-VERIFY runs, and the step-6 window is zero bits.

A verifier that hardcodes either assumption, top bit set or `emLen == k`, passes the entire current corpus, and can get one of these cases right while failing the other.

I'd like to contribute two new files, `rsa_pss_2047_sha256_mgf1_32_test.json` and `rsa_pss_2041_sha256_mgf1_32_test.json` (SHA-256, MGF1-SHA256, salt length 32, one key each), with the same case set as the existing PSS files: valid signatures, modified-signature and wrong-salt cases, and boundary cases aimed at the alignment logic, meaning encodings with the window bits set and signatures equal to and just above the modulus. Generated with the `vectorgen` workflow from doc/vectorgen.md, source name `github/c4milo/non-byte-aligned-modulus`.

Does this fit as new files, or would you rather have the groups added to an existing file instead?

Start with doc/vectorgen.md and the existing rsa_* PSS JSON vectors in testvectors_v1; run the vectorgen workflow with the stated source name and parameters. Done means the two requested 2047- and 2041-bit files contain the existing valid, modified-signature, wrong-salt, and alignment-boundary cases and follow repository conventions.

Written by the indexing model from the issue text.