feat: implement Watchtower theme for web UI

Replace Pico CSS with custom Watchtower theme (Sci-Fi Dark Mode):
- Add backend/static/ directory with Watchtower CSS files
- tokens_watchtower.css: Design tokens (colors, typography, spacing)
- theme_watchtower.css: Theme overrides for components

Features:
- High-contrast dark mode (#0b0f14 background)
- Neon accent color (#00e08f teal/cyan)
- Glow effects on buttons and inputs
- Radial gradient background
- SVG noise texture overlay (bg-noise class)
- Pill-shaped buttons (border-radius: 999px)
- Uppercase labels with letter-spacing
- Monospace font for logs

UI Enhancements:
- FastAPI static files mount added
- Custom styling for all components (sections, buttons, inputs, forms)
- Accent border-left on header and update status
- Improved visual hierarchy with color coding
- OIDC button gets secondary style (outline)

Complete US_000024 and TASK_000024.
Based on minecraft-watchtower UI design.
All Pico CSS dependencies removed.

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

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

backend/app.py

@@ -3,6 +3,7 @@ from typing import List
 
 from fastapi import Body, Depends, FastAPI, HTTPException, Request, Response, status
 from fastapi.responses import HTMLResponse, RedirectResponse
+from fastapi.staticfiles import StaticFiles
 from fastapi.templating import Jinja2Templates
 
 from backend import actions
@@ -37,6 +38,7 @@ logging.basicConfig(
 logger = logging.getLogger("skd")
 
 app = FastAPI(title="Safe Kiddo Daemon", version="1.0.0")
+app.mount("/static", StaticFiles(directory="backend/static"), name="static")
 templates = Jinja2Templates(directory="backend/templates")