Refactor: Extract common viewport initialization pattern

[yimsk]

Summary

Extract duplicated viewport initialization code across 6 views into a shared utility.

Current Duplication

Exact same 8-line block in 6 views:

View	Location
LogView	log_view.go:411-419
DetailView	detail_view.go:222-228
DiffView	diff_view.go:108-114
HelpView	help_view.go:177-183
MultiSelector	multi_selector.go:370-376
ServiceBrowser	service_browser.go:650-656

// Identical pattern in all views
if !v.ready {
    v.viewport = viewport.New(viewport.WithWidth(width), viewport.WithHeight(viewportHeight))
    v.ready = true
} else {
    v.viewport.SetWidth(width)
    v.viewport.SetHeight(viewportHeight)
}

Proposed Solution

New file: internal/view/viewport_helper.go

package view

import "charm.land/bubbles/v2/viewport"

// ViewportState wraps viewport with ready flag for safe initialization
type ViewportState struct {
    Viewport viewport.Model
    Ready    bool
}

// SetSize initializes or updates viewport dimensions
func (vs *ViewportState) SetSize(width, height int) {
    if !vs.Ready {
        vs.Viewport = viewport.New(viewport.WithWidth(width), viewport.WithHeight(height))
        vs.Ready = true
    } else {
        vs.Viewport.SetWidth(width)
        vs.Viewport.SetHeight(height)
    }
}

// MinHeight ensures viewport height is at least minHeight
func MinHeight(calculated, minHeight int) int {
    if calculated < minHeight {
        return minHeight
    }
    return calculated
}

Impact

• Lines removed: ~48 lines of duplication
• Files simplified: 6 view files
• Maintainability: Single source of truth for viewport init pattern

Related

• Part of view layer consistency improvement
• Identified during Feature Proposal: Internal Log Streamer #29 CloudWatch Logs viewer review