fix: improve read-loop detection — consecutive-only, correct thresholds, fix bugs

Follow-up to PR #705 (merged from 0xbyt4). Addresses several issues:

1. CONSECUTIVE-ONLY TRACKING: Redesigned the read/search tracker to only
   warn/block on truly consecutive identical calls. Any other tool call
   in between (write, patch, terminal, etc.) resets the counter via
   notify_other_tool_call(), called from handle_function_call() in
   model_tools.py. This prevents false blocks in read→edit→verify flows.

2. THRESHOLD ADJUSTMENT: Warn on 3rd consecutive (was 2nd), block on
   4th+ consecutive (was 3rd+). Gives the model more room before
   intervening.

3. TUPLE UNPACKING BUG: Fixed get_read_files_summary() which crashed on
   search keys (5-tuple) when trying to unpack as 3-tuple. Now uses a
   separate read_history set that only tracks file reads.

4. WEB_EXTRACT DOCSTRING: Reverted incorrect removal of 'title' from
   web_extract return docs in code_execution_tool.py — the field IS
   returned by web_tools.py.

5. TESTS: Rewrote test_read_loop_detection.py (35 tests) to cover
   consecutive-only behavior, notify_other_tool_call, interleaved
   read/search, and summary-unaffected-by-searches.

tools/code_execution_tool.py

@@ -78,7 +78,7 @@ _TOOL_STUBS = {
     "web_extract": (
         "web_extract",
         "urls: list",
-        '"""Extract content from URLs. Returns dict with results list of {url, content, error}."""',
+        '"""Extract content from URLs. Returns dict with results list of {url, title, content, error}."""',
         '{"urls": urls}',
     ),
     "read_file": (
@@ -616,7 +616,7 @@ _TOOL_DOC_LINES = [
      "    Returns {\"data\": {\"web\": [{\"url\", \"title\", \"description\"}, ...]}}"),
     ("web_extract",
      "  web_extract(urls: list[str]) -> dict\n"
-     "    Returns {\"results\": [{\"url\", \"content\", \"error\"}, ...]} where content is markdown"),
+     "    Returns {\"results\": [{\"url\", \"title\", \"content\", \"error\"}, ...]} where content is markdown"),
     ("read_file",
      "  read_file(path: str, offset: int = 1, limit: int = 500) -> dict\n"
      "    Lines are 1-indexed. Returns {\"content\": \"...\", \"total_lines\": N}"),