Windows: Password Cache Causes Excessive Argon2 KDF Delays with High PIM Values #1981

Source verification against VeraCrypt 1.26.30

The Windows password-cache path still contains the behavior described in this issue.

1. In [src/Common/Cache.c](https://github.com/veracrypt/VeraCrypt/blob/VeraCrypt_1.26.30/src/Common/Cache.c#L58-L151), ReadVolumeHeaderWCacheWithAbort() stores cached passwords and PIM values, but does not retain the PRF/KDF that successfully opened each volume.

2. When the supplied password is empty, the function iterates through cached passwords and calls ReadVolumeHeaderWithAbort() for each candidate using the same pkcs5_prf and the candidate's cached PIM.

3. The Windows driver invokes this function through [src/Driver/Ntvol.c](https://github.com/veracrypt/VeraCrypt/blob/VeraCrypt_1.26.30/src/Driver/Ntvol.c#L622-L652).

4. With KDF autodetection enabled and PIM values above 31, unsuccessful cached-password attempts can enter the expensive Argon2 derivation path. This can require approximately 1 GiB of memory per attempt, with computational cost increasing alongside PIM.

The Linux/macOS cache work in [PR #1972](#1972) does not cover the Windows driver. Its description explicitly identifies src/Common/Cache.c as unchanged. The same Windows-side limitation is also documented in [#1969](#1969).

Version reviewed: VeraCrypt 1.26.30
Tag: [VeraCrypt_1.26.30](https://github.com/veracrypt/VeraCrypt/tree/VeraCrypt_1.26.30)
Runtime qualification: The original Windows behavior was reported on 1.26.29. The persistence in 1.26.30 is confirmed by source inspection, not by a new runtime reproduction on that release.