feat: complete Epic 0 — foundation migration & infrastructure setup

Stories 0.2-0.5: rename folders→declarations (backend+frontend), configure
Redis for cache/queue/sessions, add foundation database migrations
(permissions, archived_at), replace DeclarationStatus enum with architecture
lifecycle values, create DeclarationObserver for status transition validation
and auto-archive, fix controller status transitions to respect observer rules.

93 tests pass (240 assertions).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/Models/Declaration.php

@@ -0,0 +1,170 @@
+<?php
+
+namespace App\Models;
+
+use App\Enums\DeclarationPriority;
+use App\Enums\DeclarationStatus;
+use App\Enums\DeclarationType;
+use Illuminate\Database\Eloquent\Builder;
+use Illuminate\Database\Eloquent\Factories\HasFactory;
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+use Illuminate\Database\Eloquent\Relations\HasMany;
+use Illuminate\Database\Eloquent\SoftDeletes;
+use Spatie\Activitylog\LogOptions;
+use Spatie\Activitylog\Traits\LogsActivity;
+use Spatie\MediaLibrary\HasMedia;
+use Spatie\MediaLibrary\InteractsWithMedia;
+
+class Declaration extends Model implements HasMedia
+{
+    /** @use HasFactory<\Database\Factories\DeclarationFactory> */
+    use HasFactory, InteractsWithMedia, LogsActivity, SoftDeletes;
+
+    protected $table = 'declarations';
+
+    /**
+     * The attributes that are mass assignable.
+     *
+     * @var list<string>
+     */
+    protected $fillable = [
+        'workspace_id',
+        'client_id',
+        'created_by',
+        'title',
+        'type',
+        'period_year',
+        'period_month',
+        'period_quarter',
+        'due_date',
+        'status',
+        'priority',
+        'assigned_to',
+        'validated_at',
+        'closed_at',
+        'confirmation_requested_at',
+        'confirmation_media_id',
+        'confirmed_by_type',
+        'confirmed_by_id',
+        'confirmation_signature',
+        'refused_at',
+        'refusal_reason',
+        'notes_internal',
+        'notes_client',
+        'archived_at',
+        'created_at',
+    ];
+
+    /**
+     * Get the attributes that should be cast.
+     *
+     * @return array<string, string>
+     */
+    protected function casts(): array
+    {
+        return [
+            'type' => DeclarationType::class,
+            'status' => DeclarationStatus::class,
+            'priority' => DeclarationPriority::class,
+            'validated_at' => 'datetime',
+            'closed_at' => 'datetime',
+            'confirmation_requested_at' => 'datetime',
+            'refused_at' => 'datetime',
+            'archived_at' => 'datetime',
+            'due_date' => 'date',
+        ];
+    }
+
+    /**
+     * Register media collections.
+     */
+    public function registerMediaCollections(): void
+    {
+        $this->addMediaCollection('documents')->useDisk('local');
+    }
+
+    /**
+     * Get the workspace that owns the declaration.
+     *
+     * @return BelongsTo<Workspace, $this>
+     */
+    public function workspace(): BelongsTo
+    {
+        return $this->belongsTo(Workspace::class);
+    }
+
+    /**
+     * Get the client that owns the declaration.
+     *
+     * @return BelongsTo<Client, $this>
+     */
+    public function client(): BelongsTo
+    {
+        return $this->belongsTo(Client::class);
+    }
+
+    /**
+     * Get the user who created the declaration.
+     *
+     * @return BelongsTo<User, $this>
+     */
+    public function creator(): BelongsTo
+    {
+        return $this->belongsTo(User::class, 'created_by');
+    }
+
+    /**
+     * Get the user assigned to the declaration.
+     *
+     * @return BelongsTo<User, $this>
+     */
+    public function assignee(): BelongsTo
+    {
+        return $this->belongsTo(User::class, 'assigned_to');
+    }
+
+    /**
+     * Get the messages for the declaration.
+     *
+     * @return HasMany<Message>
+     */
+    public function messages(): HasMany
+    {
+        return $this->hasMany(Message::class);
+    }
+
+    /**
+     * Get the invitations for the declaration.
+     *
+     * @return HasMany<DeclarationInvitation>
+     */
+    public function invitations(): HasMany
+    {
+        return $this->hasMany(DeclarationInvitation::class);
+    }
+
+    /**
+     * Scope a query to only include active (non-archived) declarations.
+     */
+    public function scopeActive(Builder $query): Builder
+    {
+        return $query->whereNull('archived_at');
+    }
+
+    /**
+     * Scope a query to only include archived declarations.
+     */
+    public function scopeArchived(Builder $query): Builder
+    {
+        return $query->whereNotNull('archived_at');
+    }
+
+    public function getActivitylogOptions(): LogOptions
+    {
+        return LogOptions::defaults()
+            ->logFillable()
+            ->logOnlyDirty()
+            ->dontSubmitEmptyLogs();
+    }
+}