feat(gateway): tinyfish web search as fallback when wikipedia misses

- new tinyFishSearch module: GET api.search.tinyfish.ai with X-API-Key,
  maps top-3 to SearchResult shape, never throws (all failure modes -> [])
- wikipediaSearch: on wiki miss, one tinyfish attempt; hits cached 6h
  under the same key so fallback latency is paid once
- termGlossary: on summary miss, top tinyfish hit becomes the definition
  (persisted permanently like wiki defs); miss keeps 1h sentinel
- config: TINYFISH_API_KEY (empty = fallback disabled), ENABLED,
  BASE_URL, TIMEOUT_MS, LOCATION, LANGUAGE knobs
- tests: 6 coverage for disabled/mapping/non-OK/network/bad-json

API key NOT committed — set TINYFISH_API_KEY in BWS gmw secrets.

Verified: typecheck + lint clean, 216/216 tests pass, live probe
'gubernur jawa barat' returned 3 mapped results

services/discord-gateway/src/shared/config/index.ts

@@ -132,6 +132,22 @@ export const configSchema = z
     WIKIPEDIA_LANG: z.string().min(1).default("id"),
     // Per-request timeout (ms) for Wikipedia API calls.
     WIKIPEDIA_TIMEOUT_MS: z.coerce.number().positive().default(8000),
+    // ── TinyFish web search (fallback when Wikipedia misses) ─────────────
+    // GET {base}?query=..&location=..&language=.. with X-API-Key header.
+    // Empty key = fallback disabled (Wikipedia-only, tests stay offline).
+    TINYFISH_API_KEY: z.string().optional().default(""),
+    TINYFISH_SEARCH_ENABLED: z
+      .string()
+      .optional()
+      .transform((v) => v === "true")
+      .default(true),
+    TINYFISH_SEARCH_BASE_URL: z
+      .string()
+      .url()
+      .default("https://api.search.tinyfish.ai"),
+    TINYFISH_SEARCH_TIMEOUT_MS: z.coerce.number().positive().default(10000),
+    TINYFISH_SEARCH_LOCATION: z.string().min(1).default("US"),
+    TINYFISH_SEARCH_LANGUAGE: z.string().min(1).default("en"),
     // ── Voice PCM WebSocket (direct gateway→backend, bypasses Redis) ────
     VOICE_PCM_WS_ENABLED: z
       .string()