feat: add Firecrawl backend for WebSearch and WebFetch tools

WebSearch is currently disabled for all non-Anthropic providers (OpenAI
shim, DeepSeek, Ollama, etc.) because those providers have no native
search backend. This adds Firecrawl as a fallback that activates when
FIRECRAWL_API_KEY is set, unlocking web search for every model
openclaude supports.

WebFetch uses basic HTTP + Turndown for HTML-to-markdown conversion,
which fails silently on JS-rendered SPAs and bot-protected pages.
Firecrawl scrape replaces the fetch layer when FIRECRAWL_API_KEY is set,
returning clean markdown that handles dynamic content correctly.

Changes:
- WebSearchTool: add runFirecrawlSearch() using @mendable/firecrawl-js,
  respects allowed_domains (post-filter) and blocked_domains (-site: operators),
  includes result snippets alongside links. shouldUseFirecrawl() ensures
  firstParty/Vertex/Foundry/Codex providers keep their native backends.
- WebFetchTool: add scrapeWithFirecrawl(), drops into the existing
  applyPromptToMarkdown() pipeline so prompt processing is unchanged.
- Remove "Web search is only available in the US" restriction from
  prompt when Firecrawl is active (it works globally).

bun.lock

@@ -13,6 +13,7 @@
         "@anthropic-ai/vertex-sdk": "0.14.4",
         "@commander-js/extra-typings": "12.1.0",
         "@growthbook/growthbook": "1.6.5",
+        "@mendable/firecrawl-js": "^4.18.1",
         "@modelcontextprotocol/sdk": "1.29.0",
         "@opentelemetry/api": "1.9.1",
         "@opentelemetry/api-logs": "0.214.0",
@@ -185,6 +186,8 @@
 
     "@js-sdsl/ordered-map": ["@js-sdsl/ordered-map@4.4.2", "", {}, "sha512-iUKgm52T8HOE/makSxjqoWhe95ZJA1/G1sYsGev2JDKUSS14KAgg1LHb+Ba+IPow0xflbnSkOsZcO08C7w1gYw=="],
 
+    "@mendable/firecrawl-js": ["@mendable/firecrawl-js@4.18.1", "", { "dependencies": { "axios": "1.14.0", "firecrawl": "4.16.0", "typescript-event-target": "^1.1.1", "zod": "^3.23.8", "zod-to-json-schema": "^3.23.0" } }, "sha512-NfmJv+xcHoZthj8I3NP/8KAgO8EWcvOcTvCAvszxqs7/6sCs1CRss6Tum6RycZNSwJkr5RzQossN89IlixRfng=="],
+
     "@mixmark-io/domino": ["@mixmark-io/domino@2.2.0", "", {}, "sha512-Y28PR25bHXUg88kCV7nivXrP2Nj2RueZ3/l/jdx6J9f8J4nsEGcgX0Qe6lt7Pa+J79+kPiJU3LguR6O/6zrLOw=="],
 
     "@modelcontextprotocol/sdk": ["@modelcontextprotocol/sdk@1.29.0", "", { "dependencies": { "@hono/node-server": "^1.19.9", "ajv": "^8.17.1", "ajv-formats": "^3.0.1", "content-type": "^1.0.5", "cors": "^2.8.5", "cross-spawn": "^7.0.5", "eventsource": "^3.0.2", "eventsource-parser": "^3.0.0", "express": "^5.2.1", "express-rate-limit": "^8.2.1", "hono": "^4.11.4", "jose": "^6.1.3", "json-schema-typed": "^8.0.2", "pkce-challenge": "^5.0.0", "raw-body": "^3.0.0", "zod": "^3.25 || ^4.0", "zod-to-json-schema": "^3.25.1" }, "peerDependencies": { "@cfworker/json-schema": "^4.1.1" }, "optionalPeers": ["@cfworker/json-schema"] }, "sha512-zo37mZA9hJWpULgkRpowewez1y6ML5GsXJPY8FI0tBBCd77HEvza4jDqRKOXgHNn867PVGCyTdzqpz0izu5ZjQ=="],
@@ -495,6 +498,8 @@
 
     "find-up": ["find-up@4.1.0", "", { "dependencies": { "locate-path": "^5.0.0", "path-exists": "^4.0.0" } }, "sha512-PpOwAdQ/YlXQ2vj8a3h8IipDuYRi3wceVQQGYWxNINccq40Anw7BlsEXCMbt1Zt+OLA6Fq9suIpIWD0OsnISlw=="],
 
+    "firecrawl": ["firecrawl@4.16.0", "", { "dependencies": { "axios": "^1.13.5", "typescript-event-target": "^1.1.1", "zod": "^3.23.8", "zod-to-json-schema": "^3.23.0" } }, "sha512-7SJ/FWhZBtW2gTCE/BsvU+gbfIpfTq+D9IH82l9MacauLVptaY6EdYAhrK3YSMC9yr5NxvxRcpZKcXG/nqjiiQ=="],
+
     "follow-redirects": ["follow-redirects@1.15.11", "", {}, "sha512-deG2P0JfjrTxl50XGCDyfI97ZGVCxIpfKYmfyrQ54n5FO/0gfIES8C/Psl6kWVDolizcaaxZJnTS0QSMxvnsBQ=="],
 
     "form-data": ["form-data@4.0.5", "", { "dependencies": { "asynckit": "^0.4.0", "combined-stream": "^1.0.8", "es-set-tostringtag": "^2.1.0", "hasown": "^2.0.2", "mime-types": "^2.1.12" } }, "sha512-8RipRLol37bNs2bhoV67fiTEvdTrbMUYcFTiy3+wuuOnUog2QBHCZWXDRijWQfAkhBj2Uf5UnVaiWwA5vdd82w=="],
@@ -767,6 +772,8 @@
 
     "typescript": ["typescript@5.9.3", "", { "bin": { "tsc": "bin/tsc", "tsserver": "bin/tsserver" } }, "sha512-jl1vZzPDinLr9eUt3J/t7V6FgNEw9QjvBPdysz9KfQDD41fQrC2Y4vKQdiaUpFT4bXlb1RHhLpp8wtm6M5TgSw=="],
 
+    "typescript-event-target": ["typescript-event-target@1.1.2", "", {}, "sha512-TvkrTUpv7gCPlcnSoEwUVUBwsdheKm+HF5u2tPAKubkIGMfovdSizCTaZRY/NhR8+Ijy8iZZUapbVQAsNrkFrw=="],
+
     "undici": ["undici@7.24.6", "", {}, "sha512-Xi4agocCbRzt0yYMZGMA6ApD7gvtUFaxm4ZmeacWI4cZxaF6C+8I8QfofC20NAePiB/IcvZmzkJ7XPa471AEtA=="],
 
     "undici-types": ["undici-types@7.18.2", "", {}, "sha512-AsuCzffGHJybSaRrmr5eHr81mwJU3kjw6M+uprWvCXiNeN9SOGwQ3Jn8jb8m3Z6izVgknn1R0FTCEAP2QrLY/w=="],