Release v0.7.0 - Spanish i18n & UI improvements

What's New

🌐 Language Unification

• All UI strings unified to Spanish via centralized src/shared/i18n/strings.js
• ~80 strings across 9 namespaces (nav, dropzone, imageInfo, analysis, errors, common, charts, aria, index)
• HTML templates use inline Spanish text
• JS builders import strings via dot-notation

🎨 UI Improvements

• Fixed AnalysisPanel empty state visibility bug (was showing alongside histogram)
• Improved AnalysisPanel padding and tab spacing
• Increased histogram height for better visibility (45% → 50%)
• Hidden ImageInfoPanel browse button until image is loaded (redundant at start)

🐛 Bug Fixes

• Empty state now properly hides when histogram data is available
• Histogram containers hidden by default, shown only when image loaded
• Browse button in ImageInfoPanel now contextual (only visible when image loaded)

Technical Details

• 15 files changed, 281 insertions, 94 deletions
• Pure string extraction — no logic changes
• Build passes clean with zero errors