[pranithraoibm]

• Extracts the shared reducer cases and four callbacks into Shared/hooks/useDeployFlowReducer.ts
• Moves RESET_STATE out of SharedDeployFlowAction and into each flow's own ACTION_TYPES and DeployFlowAction union — the shared reducer never handled it, each flow resets to its own initial state
• Extracts BASE_INITIAL_STATE into Shared/utils/formData.ts — both getInitialState functions spread it and only declare their own flow-specific fields
• Moves SHOW_DEPLOY_TOAST / HIDE_DEPLOY_TOAST into the shared reducer — they previously only existed in the DA flow; Services gains them here so DeployTearsheetShell (PR 7) can read deployToastOpen from both flows.