Rebrand SooSeF to FieldWitness

Complete project rebrand for better positioning in the press freedom
and digital security space. FieldWitness communicates both field
deployment and evidence testimony — appropriate for the target audience
of journalists, NGOs, and human rights organizations.

Rename mapping:
- soosef → fieldwitness (package, CLI, all imports)
- soosef.stegasoo → fieldwitness.stego
- soosef.verisoo → fieldwitness.attest
- ~/.soosef/ → ~/.fwmetadata/ (innocuous data dir name)
- SOOSEF_DATA_DIR → FIELDWITNESS_DATA_DIR
- SoosefConfig → FieldWitnessConfig
- SoosefError → FieldWitnessError

Also includes:
- License switch from MIT to GPL-3.0
- C2PA bridge module (Phase 0-2 MVP): cert.py, export.py, vendor_assertions.py
- README repositioned to lead with provenance/federation, stego backgrounded
- Threat model skeleton at docs/security/threat-model.md
- Planning docs: docs/planning/c2pa-integration.md, docs/planning/gtm-feasibility.md

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

frontends/web/templates/account.html

@@ -1,6 +1,6 @@
 {% extends "base.html" %}
 
-{% block title %}Account - Stegasoo{% endblock %}
+{% block title %}Account - Stego{% endblock %}
 
 {% block content %}
 <div class="row justify-content-center">
@@ -269,16 +269,16 @@
 
 {% block scripts %}
 <script src="{{ url_for('static', filename='js/auth.js') }}"></script>
-<script src="{{ url_for('static', filename='js/soosef.js') }}"></script>
+<script src="{{ url_for('static', filename='js/fieldwitness.js') }}"></script>
 {% if is_admin %}
 <script src="{{ url_for('static', filename='js/qrcode.min.js') }}"></script>
 {% endif %}
 <script>
-StegasooAuth.initPasswordConfirmation('accountForm', 'newPasswordInput', 'newPasswordConfirmInput');
+StegoAuth.initPasswordConfirmation('accountForm', 'newPasswordInput', 'newPasswordConfirmInput');
 
 // Webcam QR scanning for channel key input (v4.1.5)
 document.getElementById('scanChannelKeyBtn')?.addEventListener('click', function() {
-    Stegasoo.showQrScanner((text) => {
+    Stego.showQrScanner((text) => {
         const input = document.getElementById('channelKeyInput');
         if (input) {
             // Clean and format the key
@@ -294,7 +294,7 @@ document.getElementById('scanChannelKeyBtn')?.addEventListener('click', function
 
 // Format channel key input as user types
 document.getElementById('channelKeyInput')?.addEventListener('input', function() {
-    Stegasoo.formatChannelKeyInput(this);
+    Stego.formatChannelKeyInput(this);
 });
 
 function renameKey(keyId, currentName) {
@@ -336,7 +336,7 @@ document.getElementById('qrDownload')?.addEventListener('click', function() {
     const keyName = document.getElementById('qrKeyName').textContent;
     if (canvas) {
         const link = document.createElement('a');
-        link.download = 'stegasoo-channel-key-' + keyName.toLowerCase().replace(/\s+/g, '-') + '.png';
+        link.download = 'stego-channel-key-' + keyName.toLowerCase().replace(/\s+/g, '-') + '.png';
         link.href = canvas.toDataURL('image/png');
         link.click();
     }