feat: add web UI with login, CRUD, admin, and API key management

- Add login page with JWT authentication
- Add dashboard with stats and quick actions
- Add links management page (full CRUD with search)
- Add collections management page
- Add API key management page with copy-to-clipboard
- Add admin user management page (admin only)
- Fix UUID type mismatches across all endpoints
- Add updated_at column to api_keys and audit_log in schema.sql
- Fix DB_PASSWORD default in docker-compose.yml
- Add PyJWT to requirements.txt
- Fix API docs URL (/docs instead of /api/docs)
- Improve JS error handling (show actual messages)
- Rewrite conftest.py with proper DB lifecycle management
- Add 42 new integration tests (84 total, all passing)
  - test_admin.py: 15 tests for admin endpoints
  - test_auth_extended.py: 9 tests for API key CRUD
  - test_tags.py: 12 tests for tag endpoints
  - test_sync.py: 6 tests for sync endpoints

LinkSyncServer/templates/apikeys.html

@@ -0,0 +1,70 @@
+{% extends "base.html" %}
+
+{% block title %}API Keys - LinkSync{% endblock %}
+
+{% block content %}
+<div class="page-header">
+    <h1>API Keys</h1>
+    <button class="btn btn-primary" id="new-key-btn">+ New API Key</button>
+</div>
+
+<div id="api-keys-list" class="api-keys-table">
+    <div class="loading">Loading API keys...</div>
+</div>
+
+<div id="key-modal" class="modal" style="display: none;">
+    <div class="modal-overlay"></div>
+    <div class="modal-content">
+        <div class="modal-header">
+            <h2>Create API Key</h2>
+            <button class="modal-close" id="key-modal-close">&times;</button>
+        </div>
+        <form id="key-form">
+            <div class="form-group">
+                <label for="key-name">Key Name *</label>
+                <input type="text" id="key-name" placeholder="e.g., Firefox Extension" required>
+            </div>
+            <div class="form-actions">
+                <button type="button" class="btn btn-secondary" id="key-cancel-btn">Cancel</button>
+                <button type="submit" class="btn btn-primary" id="key-save-btn">Create</button>
+            </div>
+        </form>
+    </div>
+</div>
+
+<div id="key-result-modal" class="modal" style="display: none;">
+    <div class="modal-overlay"></div>
+    <div class="modal-content">
+        <div class="modal-header">
+            <h2>API Key Created</h2>
+            <button class="modal-close" id="key-result-close">&times;</button>
+        </div>
+        <div class="key-result">
+            <p><strong>Copy this key now. You will not be able to see it again.</strong></p>
+            <div class="key-display">
+                <code id="new-key-value"></code>
+                <button class="btn btn-sm" id="copy-key-btn">Copy</button>
+            </div>
+        </div>
+        <div class="form-actions">
+            <button class="btn btn-primary" id="key-done-btn">Done</button>
+        </div>
+    </div>
+</div>
+
+<div id="delete-key-modal" class="modal" style="display: none;">
+    <div class="modal-overlay"></div>
+    <div class="modal-content modal-sm">
+        <h2>Delete API Key</h2>
+        <p>Are you sure you want to delete this API key? Any connections using this key will stop working.</p>
+        <div class="form-actions">
+            <button class="btn btn-secondary" id="delete-key-cancel-btn">Cancel</button>
+            <button class="btn btn-danger" id="confirm-delete-key-btn">Delete</button>
+        </div>
+    </div>
+</div>
+{% endblock %}
+
+{% block extra_js %}
+<script src="/static/js/apikeys-page.js"></script>
+{% endblock %}