feat(auth): implement web authentication with Keycloak OAuth2

- Add auth routes: /auth/login, /auth/callback, /auth/logout
- Add OAuth2 flow with Keycloak using HTTP-only cookies
- Add web auth dependencies with role checking
- Add profile page (read-only) at /web/profile
- Update header with user menu (sign in/out, profile)
- Filter posts based on user permissions (hide drafts from guests)
- Conditionally show/hide create/edit/delete buttons
- Add authorization rules documentation to AGENTS.md
- Secure post editing/deletion endpoints with auth checks
- Add can_edit, can_delete flags to templates

app/presentation/templates/pages/profile.html

@@ -0,0 +1,125 @@
+{% extends "base.html" %}
+
+{% block title %}Profile - {{ user.username }}{% endblock %}
+
+{% block content %}
+<div class="page-header" data-testid="page-header-profile">
+    <h1 class="page-title" data-testid="page-title-profile">User Profile</h1>
+</div>
+
+<div class="card" data-testid="profile-card">
+    <div class="card-body" data-testid="profile-card-body">
+        <div class="profile-header" data-testid="profile-header">
+            <div class="avatar avatar-lg" data-testid="profile-avatar">
+                {{ user.username[0]|upper }}
+            </div>
+            <div class="profile-info" data-testid="profile-info">
+                <h2 class="profile-username" data-testid="profile-username">{{ user.username }}</h2>
+                <span class="badge {% if user_role == 'admin' %}badge-primary{% else %}badge-success{% endif %}" data-testid="profile-role">
+                    {{ user_role|upper }}
+                </span>
+            </div>
+        </div>
+
+        <div class="divider" data-testid="profile-divider"></div>
+
+        <div class="profile-details" data-testid="profile-details">
+            <div class="profile-field" data-testid="profile-field-email">
+                <span class="profile-label" data-testid="profile-label-email">Email:</span>
+                <span class="profile-value" data-testid="profile-value-email">{{ user.email or 'Not provided' }}</span>
+            </div>
+
+            <div class="profile-field" data-testid="profile-field-userid">
+                <span class="profile-label" data-testid="profile-label-userid">User ID:</span>
+                <span class="profile-value" data-testid="profile-value-userid">{{ user.user_id }}</span>
+            </div>
+
+            {% if user.first_name or user.last_name %}
+            <div class="profile-field" data-testid="profile-field-name">
+                <span class="profile-label" data-testid="profile-label-name">Name:</span>
+                <span class="profile-value" data-testid="profile-value-name">
+                    {{ user.first_name or '' }} {{ user.last_name or '' }}
+                </span>
+            </div>
+            {% endif %}
+        </div>
+    </div>
+
+    <div class="card-footer" data-testid="profile-card-footer">
+        <div class="flex justify-between items-center" data-testid="profile-actions">
+            <a href="/web/" class="btn" data-testid="btn-back-home">
+                <svg width="16" height="16" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg" style="margin-right: 0.5rem;">
+                    <path d="M10 12L6 8L10 4" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"/>
+                </svg>
+                Back to Home
+            </a>
+
+            {% if can_create %}
+            <a href="/web/posts/new" class="btn btn-primary" data-testid="btn-create-post-profile">
+                <svg width="16" height="16" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg" style="margin-right: 0.5rem;">
+                    <path d="M8 2v12M2 8h12" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"/>
+                </svg>
+                New Post
+            </a>
+            {% endif %}
+        </div>
+    </div>
+</div>
+
+<style>
+.profile-header {
+    display: flex;
+    align-items: center;
+    gap: 1.5rem;
+    margin-bottom: 1rem;
+}
+
+.profile-info {
+    display: flex;
+    flex-direction: column;
+    gap: 0.5rem;
+}
+
+.profile-username {
+    margin: 0;
+    font-size: 1.5rem;
+}
+
+.profile-details {
+    display: flex;
+    flex-direction: column;
+    gap: 1rem;
+}
+
+.profile-field {
+    display: flex;
+    gap: 0.5rem;
+}
+
+.profile-label {
+    font-weight: 600;
+    color: var(--color-text-light);
+    min-width: 80px;
+}
+
+.profile-value {
+    color: var(--color-text);
+}
+
+@media (max-width: 768px) {
+    .profile-header {
+        flex-direction: column;
+        text-align: center;
+    }
+
+    .profile-field {
+        flex-direction: column;
+        gap: 0.25rem;
+    }
+
+    .profile-label {
+        min-width: auto;
+    }
+}
+</style>
+{% endblock %}