fix: classify OpenRouter 'no tool use' 404 as model_not_found with fallback

When OpenRouter routes to an endpoint that does not support tool/function
calling, it returns HTTP 404 with the message 'No endpoints found that
support tool use. Try disabling "browser_back".'

The raw error body does not contain 'model not found' or any other
_MODEL_NOT_FOUND_PATTERNS entry, so it falls through to FailoverReason.unknown
with retryable=True. The retry loop wastes 3-5 attempts on the same
deterministic rejection, then surfaces a confusing generic error instead of
automatically failing over to a fallback model or provider.

Adding the OpenRouter phrase to _MODEL_NOT_FOUND_PATTERNS classifies it as
model_not_found (retryable=False, should_fallback=True), which triggers the
client-error fast-fallback path in conversation_loop.py: the agent switches
to a configured fallback model/provider before the user sees the error.

Existing buffered guidance in conversation_loop.py (the 'support tool use'
hint at line ~2967) remains intact and surfaces only if every fallback
exhausts.

agent/error_classifier.py

@@ -279,6 +279,15 @@ _MODEL_NOT_FOUND_PATTERNS = [
     "no such model",
     "unknown model",
     "unsupported model",
+    # OpenRouter returns 404 with this message when none of the candidate
+    # endpoints for the selected model support tool/function calling.
+    # Classifying this as model_not_found triggers fallback to a different
+    # model or provider that does support tools.  Without this entry the
+    # pattern falls through to ``unknown`` with ``retryable=True``, the
+    # retry loop burns all attempts on the same deterministic rejection,
+    # and the error surfaces as a confusing "model not found" message
+    # instead of automatically failing over.  See PR #58446.
+    "no endpoints found that support tool use",
 ]
 
 # Request-validation patterns — the request is malformed and will fail

package-lock.json

@@ -1902,7 +1902,6 @@
       "os": [
         "aix"
       ],
-      "peer": true,
       "engines": {
         "node": ">=18"
       }
@@ -1919,7 +1918,6 @@
       "os": [
         "android"
       ],
-      "peer": true,
       "engines": {
         "node": ">=18"
       }
@@ -1936,7 +1934,6 @@
       "os": [
         "android"
       ],
-      "peer": true,
       "engines": {
         "node": ">=18"
       }
@@ -1953,7 +1950,6 @@
       "os": [
         "android"
       ],
-      "peer": true,
       "engines": {
         "node": ">=18"
       }
@@ -1970,7 +1966,6 @@
       "os": [
         "darwin"
       ],
-      "peer": true,
       "engines": {
         "node": ">=18"
       }
@@ -1987,7 +1982,6 @@
       "os": [
         "darwin"
       ],
-      "peer": true,
       "engines": {
         "node": ">=18"
       }
@@ -2004,7 +1998,6 @@
       "os": [
         "freebsd"
       ],
-      "peer": true,
       "engines": {
         "node": ">=18"
       }
@@ -2021,7 +2014,6 @@
       "os": [
         "freebsd"
       ],
-      "peer": true,
       "engines": {
         "node": ">=18"
       }
@@ -2038,7 +2030,6 @@
       "os": [
         "linux"
       ],
-      "peer": true,
       "engines": {
         "node": ">=18"
       }
@@ -2055,7 +2046,6 @@
       "os": [
         "linux"
       ],
-      "peer": true,
       "engines": {
         "node": ">=18"
       }
@@ -2072,7 +2062,6 @@
       "os": [
         "linux"
       ],
-      "peer": true,
       "engines": {
         "node": ">=18"
       }
@@ -2089,7 +2078,6 @@
       "os": [
         "linux"
       ],
-      "peer": true,
       "engines": {
         "node": ">=18"
       }
@@ -2106,7 +2094,6 @@
       "os": [
         "linux"
       ],
-      "peer": true,
       "engines": {
         "node": ">=18"
       }
@@ -2123,7 +2110,6 @@
       "os": [
         "linux"
       ],
-      "peer": true,
       "engines": {
         "node": ">=18"
       }
@@ -2140,7 +2126,6 @@
       "os": [
         "linux"
       ],
-      "peer": true,
       "engines": {
         "node": ">=18"
       }
@@ -2157,7 +2142,6 @@
       "os": [
         "linux"
       ],
-      "peer": true,
       "engines": {
         "node": ">=18"
       }
@@ -2174,7 +2158,6 @@
       "os": [
         "linux"
       ],
-      "peer": true,
       "engines": {
         "node": ">=18"
       }
@@ -2191,7 +2174,6 @@
       "os": [
         "netbsd"
       ],
-      "peer": true,
       "engines": {
         "node": ">=18"
       }
@@ -2208,7 +2190,6 @@
       "os": [
         "netbsd"
       ],
-      "peer": true,
       "engines": {
         "node": ">=18"
       }
@@ -2225,7 +2206,6 @@
       "os": [
         "openbsd"
       ],
-      "peer": true,
       "engines": {
         "node": ">=18"
       }
@@ -2242,7 +2222,6 @@
       "os": [
         "openbsd"
       ],
-      "peer": true,
       "engines": {
         "node": ">=18"
       }
@@ -2259,7 +2238,6 @@
       "os": [
         "openharmony"
       ],
-      "peer": true,
       "engines": {
         "node": ">=18"
       }
@@ -2276,7 +2254,6 @@
       "os": [
         "sunos"
       ],
-      "peer": true,
       "engines": {
         "node": ">=18"
       }
@@ -2293,7 +2270,6 @@
       "os": [
         "win32"
       ],
-      "peer": true,
       "engines": {
         "node": ">=18"
       }
@@ -2310,7 +2286,6 @@
       "os": [
         "win32"
       ],
-      "peer": true,
       "engines": {
         "node": ">=18"
       }
@@ -2327,7 +2302,6 @@
       "os": [
         "win32"
       ],
-      "peer": true,
       "engines": {
         "node": ">=18"
       }