Add core modules, web frontend, CLI, keystore, and fieldkit

Core:
- paths.py: centralized ~/.soosef/ path constants
- config.py: JSON config loader with dataclass defaults
- exceptions.py: SoosefError hierarchy
- cli.py: unified Click CLI wrapping stegasoo + verisoo + native commands

Keystore:
- manager.py: unified key management (Ed25519 identity + channel keys)
- models.py: IdentityInfo, KeystoreStatus dataclasses
- export.py: encrypted key bundle export/import for USB transfer

Fieldkit:
- killswitch.py: ordered emergency data destruction (keys first)
- deadman.py: dead man's switch with check-in timer
- tamper.py: SHA-256 file integrity baseline + checking
- usb_monitor.py: pyudev USB whitelist enforcement
- geofence.py: haversine-based GPS boundary checking

Web frontend (Flask app factory + blueprints):
- app.py: create_app() factory with context processor
- blueprints: stego, attest, fieldkit, keys, admin
- templates: base.html (dark theme, unified nav), dashboard, all section pages
- static: CSS, favicon

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontends/web/static/favicon.svg

@@ -0,0 +1,4 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 32 32">
+  <rect width="32" height="32" rx="6" fill="#2a3a5e"/>
+  <text x="16" y="22" text-anchor="middle" font-family="system-ui" font-size="14" font-weight="bold" fill="#e5d058">SF</text>
+</svg>

frontends/web/static/style.css

@@ -0,0 +1,59 @@
+/* ============================================================================
+   SooSeF - Main Stylesheet
+   Adapted from Stegasoo's style.css — same dark theme, same patterns.
+   ============================================================================ */
+
+:root {
+    --gradient-start: #2a3a5e;
+    --gradient-end: #4a2860;
+    --bg-dark-1: #1a1a2e;
+    --bg-dark-2: #16213e;
+    --bg-dark-3: #0f3460;
+    --text-muted: rgba(255, 255, 255, 0.5);
+    --border-light: rgba(255, 255, 255, 0.1);
+    --overlay-dark: rgba(0, 0, 0, 0.3);
+    --overlay-light: rgba(255, 255, 255, 0.05);
+}
+
+/* Navbar */
+.navbar {
+    background: linear-gradient(135deg, var(--gradient-start), var(--gradient-end));
+    border-bottom: 1px solid var(--border-light);
+}
+
+.navbar-brand {
+    font-size: 1.1rem;
+    letter-spacing: 0.05em;
+}
+
+/* Nav icon + label pattern from stegasoo */
+.nav-icons .nav-link {
+    display: flex;
+    align-items: center;
+    gap: 0.4rem;
+    padding: 0.5rem 0.75rem;
+    font-size: 0.9rem;
+}
+
+.nav-icons .nav-link i {
+    font-size: 1.1rem;
+}
+
+/* Cards */
+.card {
+    transition: border-color 0.2s ease;
+}
+
+.card:hover {
+    border-color: rgba(255, 255, 255, 0.25) !important;
+}
+
+/* Footer */
+footer {
+    border-top: 1px solid var(--border-light);
+}
+
+/* Badge styling */
+.badge code {
+    font-family: 'SF Mono', 'Fira Code', monospace;
+}