feat(automations): moteur de regles if-this-then-that (v5.1.0 roadmap, bump v5.2.0)

Moteur d'automatisation complet : declencheurs (evenement / cron / bouton),
conditions combinables (eq, neq, contains, is_empty, is_not_empty, changed)
et actions (webhook, set_property, create_page, notify).

- Migration v5 : tables `automations` + `automation_runs` (avec index).
- Service `app/services/automations.py` : fire_event, cron_due (`*/N`,
  minute fixe, @hourly/@daily), scheduler de fond dans le lifespan.
- Router `app/routers/automations.py` : CRUD `/workspace/automations`,
  historique des executions, run manuel + run bouton `/api/automations/{id}/run`
  (exempt CSRF, comme `/api/agent`).
- Hooks d'evenements dans collections.py / board.py / workspace.py
  (collection.* et page.* : created/updated/deleted/moved).
- Bloc `button` dans l'editeur (menu slash) : declenche une regle au clic,
  picker d'automation inline, serialisation automations_id/name.
- Panneau Automations dans le Settings (creer/editer/activer/desactiver/
  lancer/supprimer + historique), collection scope + JSON conditions/actions.
- 11 tests `tests/test_automations.py` ; suite complete pytest 289 verte.
- Version bump 5.2.0 (VERSION, app/main.py, CHANGELOG).

app/migrations.py

@@ -172,6 +172,58 @@ def _migration_fts5(conn: sqlite3.Connection) -> None:
     )
 
 
+@register(5, "automations (v5.1.0 rules engine)")
+def _migration_automations(conn: sqlite3.Connection) -> None:
+    """v5.1.0: database automations — if-this-then-that rule engine (trigger +
+    condition + action) and clickable buttons that trigger actions.
+
+    ``automations``      — the rules (event/cron/button trigger, optional
+                           condition JSON, actions JSON, run counters).
+    ``automation_runs``  — execution history for auditing and the Settings UI.
+    """
+    conn.execute(
+        """
+        CREATE TABLE IF NOT EXISTS automations (
+            id INTEGER PRIMARY KEY AUTOINCREMENT,
+            workspace TEXT NOT NULL DEFAULT '',
+            name TEXT NOT NULL,
+            trigger_type TEXT NOT NULL DEFAULT 'event',  -- event | cron | button
+            event TEXT NOT NULL DEFAULT 'page.created',  -- for trigger_type='event'
+            cron_expression TEXT NOT NULL DEFAULT '',    -- for trigger_type='cron'
+            collection_id INTEGER,                       -- optional scope (event triggers)
+            condition_json TEXT NOT NULL DEFAULT '[]',   -- list of condition clauses
+            actions_json TEXT NOT NULL DEFAULT '[]',     -- list of action descriptors
+            enabled BOOLEAN NOT NULL DEFAULT 1,
+            created_by INTEGER,
+            last_run_at TIMESTAMP,
+            run_count INTEGER NOT NULL DEFAULT 0,
+            created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+            updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
+        )
+        """
+    )
+    conn.execute(
+        "CREATE INDEX IF NOT EXISTS idx_automations_trigger ON automations(trigger_type, event, enabled)"
+    )
+    conn.execute(
+        """
+        CREATE TABLE IF NOT EXISTS automation_runs (
+            id INTEGER PRIMARY KEY AUTOINCREMENT,
+            automation_id INTEGER NOT NULL REFERENCES automations(id) ON DELETE CASCADE,
+            trigger_source TEXT NOT NULL DEFAULT 'event',
+            status TEXT NOT NULL DEFAULT 'fired',   -- fired | skipped | error
+            detail TEXT NOT NULL DEFAULT '',
+            collection_id INTEGER,
+            page_id INTEGER,
+            created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
+        )
+        """
+    )
+    conn.execute(
+        "CREATE INDEX IF NOT EXISTS idx_automation_runs_auto ON automation_runs(automation_id, created_at)"
+    )
+
+
 @register(4, "database templates (icon) + property validation")
 def _migration_db_templates_validation(conn: sqlite3.Connection) -> None:
     """v5.3.0: database templates get an icon, properties a validation config,