💡 Add Support for Creating and Submitting Hard Fork Initiation Governance Actions

### Area

Proposal Pillar

### Is there new design needed?

No

### What?

Introduce full support in GovTool for **Hard Fork Initiation** governance actions, enabling users to create, preview, and submit this action type on-chain.

### Required Fields (per CIP-1694):
- Title
- Abstract
- Motivation
- Rationale
- Previous Governance Action Hash
- Previous Governance Action ID
- Major
- Minor
- Reference Links

### Why?

- Hard Fork Initiation is a **key governance action** defined in CIP-1694.
- Including this ensures GovTool covers the **full governance lifecycle** and supports all official action types.
- Enables DReps and technical stakeholders to propose **protocol upgrades** directly through the interface.

### How?

- Extend proposal creation flow to include a **Hard Fork Initiation** option.
- Present the required form fields dynamically.
- Validate data types, especially:
- Previous GA hash (hex format)
- Major/Minor (must be integers)

### (Optional) User Story with acceptance criteria

- [ ] “Hard Fork Initiation” action type is selectable in proposal creation.
- [ ] All specified fields are available and validated during submission.
- [ ] JSON metadata is generated correctly per CIP-1694.
- [ ] Proposal can be submitted on-chain and displayed in voting/outcomes views.