Add indexes on fluxstd table

[monodera]

This pull request introduces new database indexes to the fluxstd table to improve query performance and updates the corresponding model and documentation. Additionally, a minor logging improvement is made in the utility function for target dataframes.

Database Index Additions:

• Added two new indexes to the fluxstd table: one on input_catalog_id and fluxstd_id, and another on version and fluxstd_id, to optimize query efficiency. (alembic/pfsa-db01-gb/alembic/versions/20251216-182855_385b6cdf44f7_add_indexes_to_fluxstd.py)
• Updated the SQLAlchemy model for fluxstd to include the new indexes, ensuring consistency between the codebase and database schema. (src/targetdb/models/fluxstd.py)
• Documented the new indexes in the database schema markdown file. (docs/tbls/public.fluxstd.md)

Code Quality Improvement:

• Improved logging in the make_target_df_from_uploader utility function by using f-string formatting for clarity. (src/targetdb/utils.py)