Remove nil context fallback from libs/log (#4656)

## Summary
- Remove the `nil` context fallback from functions in `libs/log`
- Passing a nil context is an error; callers should always pass a valid
context

From https://pkg.go.dev/context:
> Do not pass a nil [Context](https://pkg.go.dev/context#Context), even
if a function permits it. Pass
[context.TODO](https://pkg.go.dev/context#TODO) if you are unsure about
which Context to use.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: pietern

libs/log/logger.go

@@ -24,9 +24,6 @@ func log(ctx context.Context, logger *slog.Logger, level slog.Level, msg string)
 	// skip [runtime.Callers, this function, this function's caller].
 	runtime.Callers(3, pcs[:])
 	r := slog.NewRecord(time.Now(), level, msg, pcs[0])
-	if ctx == nil {
-		ctx = context.Background()
-	}
 	_ = logger.Handler().Handle(ctx, r)
 }
 

libs/log/sdk.go

@@ -37,9 +37,6 @@ func (s slogAdapter) log(ctx context.Context, logger *slog.Logger, level slog.Le
 	runtime.Callers(4, pcs[:])
 	r := slog.NewRecord(time.Now(), level, msg, pcs[0])
 	r.AddAttrs(slog.Bool("sdk", true))
-	if ctx == nil {
-		ctx = context.Background()
-	}
 	_ = logger.Handler().Handle(ctx, r)
 }