refactor(V2): get_instruments common-only on /mcp (enriched with Deribit filters)

Move get_instruments off the per-exchange Deribit router and onto the
unified interface, without losing the advanced Deribit filtering.

- /mcp/tools/get_instruments now accepts the Deribit-specific filters
  (currency, kind, expiry_from/to, strike_min/max, min_open_interest) and
  pagination (offset/limit). Venues that list everything (Hyperliquid)
  ignore them. Response adds `meta: {deribit: {total, offset, limit,
  has_more}}` surfacing per-source pagination.
- Remove /mcp-deribit/tools/get_instruments (endpoint + tool wrapper +
  GetInstrumentsReq schema). The DeribitClient.get_instruments METHOD
  stays — it's what the unified normalizer calls.

Tests: cover the enriched filters + meta passthrough; app-boot asserts
/mcp-deribit/tools/get_instruments is gone. Docs (API_REFERENCE/README/
CLAUDE) and smoke updated; also fixed the stale Hyperliquid tool count
(14 → 15) found during the doc check.

325 passed, ruff clean. Verified live: kind=option limit=5 → 5/940
has_more=true; /mcp-deribit/tools/get_instruments → 404.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -61,11 +61,13 @@ Nota: nel modulo `sentiment` "bybit" resta come **fonte dati pubblica**
 
 - **`/mcp` (comune)** — gli **unici** tool dati trasversali. `get_instruments`
   (schema uniforme: `exchange`, `fees`, `history_start`, `type`, `tick_size`,
-  `native`); `get_historical` e `get_indicators` con `exchange` opzionale →
-  singolo venue se valorizzato, **consenso** multi-exchange (mediana OHLC +
-  `div_pct`) se omesso. Supporta deribit + hyperliquid (IBKR non integrato).
+  `native`; filtri/paginazione Deribit + `meta` per-sorgente); `get_historical`
+  e `get_indicators` con `exchange` opzionale → singolo venue se valorizzato,
+  **consenso** multi-exchange (mediana OHLC + `div_pct`) se omesso. Supporta
+  deribit + hyperliquid (IBKR non integrato).
 - **`/mcp-{exchange}`** — router per-exchange per il resto (ticker, ordini,
-  options analytics, …). **NON** espongono più `get_historical`/`get_indicators`.
+  options analytics, …). **NON** espongono più
+  `get_instruments`/`get_historical`/`get_indicators`.
 
 Convenzione: `get_historical` ritorna la chiave uniforme
 `candles: [{timestamp(ms), open, high, low, close, volume}]` (validatore in