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/index.html

@@ -1,19 +1,19 @@
 {% extends "base.html" %}
-{% block title %}SooSeF — Soo Security Fieldkit{% endblock %}
+{% block title %}FieldWitness — FieldWitness{% endblock %}
 
 {% block content %}
 <div class="text-center mb-5">
-    <h1 class="display-5 fw-bold">Soo Security Fieldkit</h1>
+    <h1 class="display-5 fw-bold">FieldWitness</h1>
     <p class="lead text-muted">Offline-first security toolkit for field operations</p>
 </div>
 
 <div class="row g-4">
-    {# ── Stegasoo Card ── #}
+    {# ── Stego Card ── #}
     <div class="col-md-6 col-lg-4">
         <div class="card h-100 bg-dark border-secondary">
             <div class="card-body">
                 <h5 class="card-title"><i class="bi bi-lock me-2 text-primary"></i>Encode</h5>
-                <p class="card-text text-muted">Hide encrypted messages in images or audio using Stegasoo's hybrid authentication.</p>
+                <p class="card-text text-muted">Hide encrypted messages in images or audio using Stego's hybrid authentication.</p>
                 <a href="/encode" class="btn btn-outline-primary btn-sm">Encode Message</a>
             </div>
         </div>
@@ -37,8 +37,8 @@
         </div>
     </div>
 
-    {# ── Verisoo Cards ── #}
-    {% if has_verisoo %}
+    {# ── Attest Cards ── #}
+    {% if has_attest %}
     <div class="col-md-6 col-lg-4">
         <div class="card h-100 bg-dark border-secondary">
             <div class="card-body">
@@ -102,10 +102,10 @@
                             <i class="bi bi-image me-1"></i>DCT: {{ 'Available' if has_dct else 'Unavailable' }}
                         </span>
                     </div>
-                    {% if has_verisoo %}
+                    {% if has_attest %}
                     <div class="col-auto">
                         <span class="badge bg-success">
-                            <i class="bi bi-patch-check me-1"></i>Verisoo: Active
+                            <i class="bi bi-patch-check me-1"></i>Attest: Active
                         </span>
                     </div>
                     {% endif %}