UK visa application: How to declare shareholding and dividend?

The best thing you can do when applying for a visa is to be truthful and be specific. Give as much of the correct information as possible and you will maximise your chances of getting the visa.

Now, I am not an immigration officer so I cannot guarantee that you will get a visa, but according to what you wrote I can say that you are handling this visa application correctly.

Can I attach her employment confirmation letter as evidence of economic ties to Pakistan?

Yes. You can also attach recent payslips to show that the job is real and providing steady income.

I also have a shareholding/investment in our Family business where I am listed as a Director. Should I show this under 'self-employed' category?

Yes. It makes sense to list this under self-employed. Give an explanation on what the company does and your role in it.

I have recently received a substantial payment as a profit share/dividend from my family company. This can be traced as a bank transfer from company account to my personal account. I am worried if this may be seen as fund parking as it is higher than my regular salaried remuneration.

This could be construed as funds parking if your account were empty and/or unused before receiving the payment. According to what you wrote, you have a stable job and a regular life which means that your bank statement should reflect this: constant income, regular expenses for living, stone leftover carried into the next month. Read this question to gain a better understanding of what bank statements (should) say about applicants.

Is it okay to attach the bank statements and a letter from the company certifying that this amount has been transferred as my profit share?

Yes. Add and supporting information you deem necessary.