Web UI v4.1.6: Admin settings, nav icons, air-gap ready

Admin System Settings page:
- New /admin/settings route with channel key config
- QR code export with tiled print sheet (4x5 on US Letter)
- Server config display (HTTPS, port, auth, DCT/QR status)
- Environment info (version, Python, platform, KDF)

Navigation improvements:
- Icon-only nav with floating labels on hover
- Gold labels slide down below icons
- Gradient pill background on hover

Air-gap ready:
- All vendor libs now local (Bootstrap CSS/JS, Icons, html5-qrcode)
- QRious library for QR generation
- No external CDN dependencies

Other changes:
- Moved About link from nav to footer
- Channel QR export moved from about.html to admin/settings.html
- Print sheet button for QR codes (tiled US Letter output)
- Dev runner script (dev_run.sh) with r/q hotkeys
- Fixed navbar dropdown z-index

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

PLAN-4.1.6.md

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+# Stegasoo v4.1.6 Planning
+
+## UI Tweaks
+
+### 1. Revamp Tron Lines Animation (Carrier/Stego Image)
+**Current state:**
+- 6-8 snake paths, each with 3-5 segments (~24-40 total lines)
+- 2px thick lines
+- 30-60px length per segment
+- Starting points spread across 80% of image area
+- Colors: yellow, cyan, purple, blue with glow
+
+**Target improvements:**
+- [x] Thinner lines (1px instead of 2px)
+- [x] More numerous (20-40 paths via 5x4 grid, ~60-200 segments total)
+- [x] Better distribution across entire image (grid-based seeding)
+- [x] Shorter segments (12-30px) for denser "circuit board" look
+
+**Files:**
+- `frontends/web/static/style.css` (~881-979) - `.embed-trace` styling
+- `frontends/web/static/js/stegasoo.js` (~333-390) - `generateEmbedTraces()`
+
+---
+
+## Tools Page Expansion
+
+### Analysis Tools
+- [x] **JPEG Compression Tester** - Preview image at different quality levels (10-100%), show file size delta. Useful for understanding stego survivability.
+- [ ] **LSB Plane Viewer** - Visualize least significant bit plane(s) of RGB channels. Classic stego analysis tool.
+- [ ] **Histogram Viewer** - Color distribution graph per channel. Anomalies can indicate hidden data.
+- [ ] **Image Diff** - Compare two images side-by-side with pixel difference highlighting. Great for original vs stego comparison.
+- [ ] **Noise Analysis** - Chi-square or similar statistical analysis for detecting LSB embedding.
+
+### Transform Tools
+- [x] **Rotate/Flip** - 90°/180°/270° rotation, horizontal/vertical flip
+- [ ] **Resize** - Scale with aspect ratio lock, common presets (50%, 25%, etc.)
+- [ ] **Crop** - Basic rectangular crop with preview
+- [x] **Format Convert** - PNG ↔ JPEG ↔ WebP with quality slider
+
+### Existing Tools (already done)
+- [x] Capacity Calculator
+- [x] EXIF Viewer
+- [x] EXIF Strip
+- [x] Image Peek (header analysis)
+
+### Tools UI/UX Overhaul
+
+**Final Layout: Office-style Ribbon + Two-Panel**
+```
+┌─────────────────────────────────────────────────────────────┐
+│  📏  📋  👁️  📊  ┃  ✂️  🔄  📐  🔀      Image Tools         │ ← Icon toolbar
+├────────────────────────────────────────┬────────────────────┤
+│  [Format: PNG ▼] [Quality: 85]         │                    │
+├────────────────────────────────────────┤  Capacity          │
+│                                        │  Calculator        │
+│    ┌────────────────────────────┐     │  ──────────────    │
+│    │                            │     │                    │
+│    │      Drop image here       │     │  Dimensions:       │
+│    │         or click           │     │  1920 × 1080       │
+│    │                            │     │                    │
+│    └────────────────────────────┘     │  LSB Capacity:     │
+│                                        │  245 KB            │
+│           [image.jpg]                  │                    │
+│                                        │  ──────────────    │
+│                                        │  [Clear] [Export]  │
+└────────────────────────────────────────┴────────────────────┘
+      Options + dropzone/preview             Results sidebar
+```
+
+- Top ribbon: Icon buttons grouped by category (Analyze | Transform)
+- Left panel: Tool options + dropzone/preview (INPUT)
+- Right panel: Tool name + results/metadata + actions (OUTPUT)
+- Flow: Left → Right (input → output)
+
+**Implementation Tasks:**
+- [x] Move inline CSS to style.css
+- [x] Build icon toolbar ribbon
+- [x] Build two-panel layout structure
+- [x] Migrate existing tools (Capacity, EXIF, Strip)
+- [x] Add new tools (Rotate, Compress, Convert)
+- [ ] Loading spinner on all async operations
+- [ ] Toast notifications instead of alerts
+- [ ] Consistent color coding (green=analysis, amber=transform)
+- [ ] Mobile: stack panels vertically
+
+---
+
+## CLI Improvements
+
+### (Add items here)
+
+---
+
+## Other UI Tweaks
+
+### (Add items here)
+