feat: add Flyway V9 (thresholds) and V10 (audit_log) migrations

cameleer3-server-app/src/main/resources/db/migration/V10__audit_log.sql

@@ -0,0 +1,18 @@
+CREATE TABLE audit_log (
+    id          BIGSERIAL PRIMARY KEY,
+    timestamp   TIMESTAMPTZ NOT NULL DEFAULT now(),
+    username    TEXT NOT NULL,
+    action      TEXT NOT NULL,
+    category    TEXT NOT NULL,
+    target      TEXT,
+    detail      JSONB,
+    result      TEXT NOT NULL,
+    ip_address  TEXT,
+    user_agent  TEXT
+);
+
+CREATE INDEX idx_audit_log_timestamp ON audit_log (timestamp DESC);
+CREATE INDEX idx_audit_log_username ON audit_log (username);
+CREATE INDEX idx_audit_log_category ON audit_log (category);
+CREATE INDEX idx_audit_log_action ON audit_log (action);
+CREATE INDEX idx_audit_log_target ON audit_log (target);

cameleer3-server-app/src/main/resources/db/migration/V9__admin_thresholds.sql

@@ -0,0 +1,7 @@
+CREATE TABLE admin_thresholds (
+    id          INTEGER PRIMARY KEY DEFAULT 1,
+    config      JSONB NOT NULL DEFAULT '{}',
+    updated_at  TIMESTAMPTZ NOT NULL DEFAULT now(),
+    updated_by  TEXT NOT NULL,
+    CONSTRAINT  single_row CHECK (id = 1)
+);