fix(security): resolve Critical+High findings from module audit — agent, translate, superset_client

P0 — CRITICAL (CWE-798): JWT_SECRET crash-early
  Replace hardcoded super-secret-key fallback with os.environ["JWT_SECRET"]
  and ${JWT_SECRET:?} syntax in app.py + docker-compose files

P1 — HIGH: Frontend dependency CVEs
  Upgrade svelte 5.43.8 → 5.56.4 — resolves devalue DoS (GHSA-g2pg-6438-jwpf)
  and svelte XSS (GHSA-crpf-4hrx-3jrp, GHSA-m56q-vw4c-c2cp, GHSA-rcqx-6q8c-2c42)

P2 — MEDIUM: Logging hygiene + contract gaps + tool resolver refactor
  Apply _redact_sensitive_fields() in middleware + event streaming
  Truncate LLM error body to 100 chars
  Add @RATIONALE/@REJECTED to HandleResume + SaveConversation
  Refactor deterministic intent matching → LLM-driven tool resolution

P3 — LOW: Translate logging hardening
  Move _sanitize_url() to _utils.py (shared, no circular imports)
  Sanitize base_url before logging in _llm_call.py and _llm_async_http.py
  Emit EXPLORE warning when LLM_SSL_VERIFY=false disables TLS

superset_client module: passed clean — no changes needed

backend/src/agent/langgraph_setup.py

@@ -189,8 +189,10 @@ async def create_agent(
         "managing Git operations (branch/commit/deploy), running LLM validation "
         "and documentation, creating and copying dashboards and datasets, "
         "and checking system health, environments, and task status. "
-        "If the data you need is already provided in the user message, use that directly "
-        "rather than calling tools. Only call tools when the data is not present."
+        "You handle all intent detection — multi-intent queries, negations (\"don't run\"), "
+        "synonyms (\"панели\" = \"дашборды\"), and typos are your responsibility. "
+        "Call the right tool(s) for the job. If data is already provided in context, "
+        "use it directly rather than calling redundant tools."
     )
     if env_id:
         prompt += f"\n\nCurrent environment: '{env_id}'. When calling tools that accept env_id, use this value."