Final Implementation Initiate Proposal Flow

[timpel-fcs]

Summary

This PR adds Initiate Proposal layout changes that are not covered by the component issues references in the parent issue:

• Align Initiate Proposal flow with Figma: shared layout tokens (createProposalLayout.ts), card/field column sizing, and InitiateProposalLayout wrapper.
• Restyle form CTAs and Cancel Proposal dialog via formButtonStyles and CancelProposalDialog (Figma pill buttons, discard confirmation).
• Refactor governance forms and review step: FormLayout, ProposalReviewField, updated ProposalSummary / ConfigValuesChanges, review-only header on create flow.
• Add WeightDiffIndicator for SV reward-weight changes on initiate and review steps.
• Fix config row label overlap, FormLayout spacing, and update governance form/summary tests.

Fixes #2623

Figma: https://www.figma.com/design/sXdsHZtM5c7xXQWckd6Ob8/supervalidator?node-id=0-1

Pull Request Checklist

Cluster Testing

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• If a logical synchronizer upgrade test is required (from canton-3.5), comment /lsu_test on this PR to request it, and ping someone with access to the DA-internal system to approve it.

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[timpel-fcs]

this is a draft, pending merge of the interlinked component changes for final look and feel + layout review of the initiate proposal flow

Before merging of all other components no review is required