Implement the following plan:

# Plan: Improve GetUser logging

## Context

`GetUser` in `internal/repository/user.go` (line 75) logs a `Warn` for every query error, including the common `sql.ErrNoRows` case (user not found). Two problems:

1. `sql.ErrNoRows` is a normal, expected condition — many callers check for it explicitly. It should not produce a warning.
2. The log message **omits the actual error**: `"Error while querying user '%v' from database"` gives no clue what went wrong for real failures.

This is the same pattern just fixed in `scanJob` (job.go). The established approach: suppress `sql.ErrNoRows`, add `runtime.Caller(1)` context and include `err` in real-error logs.

## Approach

Modify the `Scan` error block in `GetUser` (`internal/repository/user.go`, lines 75-79):

```go
if err := sq.Select(...).QueryRow().Scan(...); err != nil {
    if err != sql.ErrNoRows {
        _, file, line, _ := runtime.Caller(1)
        cclog.Warnf("Error while querying user '%v' from database (%s:%d): %v",
            username, filepath.Base(file), line, err)
    }
    return nil, err
}
```

Add `"path/filepath"` and `"runtime"` to imports (not currently present in user.go).

## Critical File

- `internal/repository/user.go` — only file to change (lines ~7-24 for imports, ~75-79 for error block)

## Verification

1. `go build ./...` — must compile cleanly
2. `go test ./internal/repository/...` — existing tests must pass


If you need specific details from before exiting plan mode (like exact code snippets, error messages, or content you generated), read the full transcript at: /Users/jan/.claude/projects/-Users-jan-prg-CC-cc-backend/7916ffa0-cf9e-4cb7-a75f-8a1db33c75bd.jsonl