Support FASTA input for calibration-library sequence matching

[jspaezp]

Title: Support FASTA input for calibration-library sequence matching

--calib-lib is now independent of the primary search source, including a
FASTA-predicted primary library. Calibration itself still accepts only a built
library.

Add --calib-fasta (and the matching configuration field). When sequence
features are available, match calibration peptides against predicted/search
sequences with a multi-pattern matcher such as Aho-Corasick instead of requiring
the user to materialize another spectral library.

Decide explicitly:

• whether --calib-lib and --calib-fasta are mutually exclusive;
• how modifications and I/L equivalence affect matching;
• behavior when sequence features are unavailable;
• whether calibration FASTA digestion settings share or override [library].