Daptin: SQL injection via unvalidated goqu.L() calls in aggregate API

Summary

The /aggregate/:typename endpoint accepted column and group query parameters that were passed verbatim to goqu.L() — a raw SQL literal expression builder — without any validation. This bypassed all parameterization and allowed authenticated users with any valid session to inject arbitrary SQL expressions.

Impact

An authenticated low-privilege user could:
- Extract data from any table via subquery: (SELECT group_concat(email) FROM user_account) as leak
- Disclose database internals: sqlite_version(), (SELECT sql FROM sqlite_master)
- Exfiltrate cross-table data via correlated subqueries

The vulnerability was confirmed locally; user_account.email values were extracted via a crafted column parameter by a non-admin user.

Root Cause

goqu.L(userInput) in server/resource/resource_aggregate.go inserted user-supplied query parameters directly into the SQL string with no validation.

Fix (v0.11.4)

All goqu.L() calls on user-controlled input were eliminated and replaced with:
- Structural expression parsing supporting all documented API forms
- Schema-based column validation (column names checked against entity schema via TableInfo().GetColumnByName())
- Exact-match allowlist for aggregate functions (count, sum, avg, min, max, first, last) and scalar functions (date, strftime, upper, lower, etc.)
- Safe goqu constructors (goqu.I(), goqu.SUM(), goqu.Func()) for all generated expressions
- allowedTables scope enforcement: qualified column refs (table.col) validated against root entity + explicitly joined tables only

Two additional DoS bugs were fixed in the same commit: uuid.MustParse panic on malformed UUID input and an index-out-of-range panic in ToOrderedExpressionArray on empty sort expressions.

Credits

Reported by @VashuVats.