Cherry-pick: Fix SQLite base64 blob detection (#1472)

[GingerAdonis]

Upstream PR

dimitri#1472

Summary

When SQLite driver returns blob values as strings, pgloader assumed they were base64-encoded. Fix adds a has-base64-value-p function to verify before decoding; falls back to UTF-8 encoding if not base64.

Files

• src/sources/sqlite/sqlite.lisp

Notes

• +18/-1 lines
• PR has bugs: duplicate in-package form and mismatched declaim function name (has-base64-sequence-p vs has-base64-value-p)
• Would need fixing before applying
• May fix upstream ERROR Bad character - in base64 decode dimitri/pgloader#415
• Priority: Lower — needs cleanup before applying