feat(reasoning): add inline think tag extraction and Anthropic thinking_blocks support

Add extract_think() and emit_incremental_think() helpers to extract thinking content from inline <think> and <thought> tags in the content field. This handles models served via Ollama, self-hosted vLLM, or other compatible endpoints that embed reasoning as inline tags instead of using the dedicated reasoning_content API field.

Also adds Anthropic thinking_blocks support for extended thinking via the thinking content blocks array.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

tests/utils/test_strip_think.py

@@ -1,4 +1,4 @@
-from nanobot.utils.helpers import strip_think
+from nanobot.utils.helpers import extract_think, strip_think
 
 
 class TestStripThinkTag:
@@ -144,3 +144,84 @@ class TestStripThinkConservativePreserve:
     def test_literal_channel_marker_in_code_block_preserved(self):
         text = "Example:\n```\nif line.startswith('<channel|>'):\n    skip()\n```"
         assert strip_think(text) == text
+
+
+class TestExtractThink:
+
+    def test_no_think_tags(self):
+        thinking, clean = extract_think("Hello World")
+        assert thinking is None
+        assert clean == "Hello World"
+
+    def test_single_think_block(self):
+        text = "Hello <think>reasoning content\nhere</think> World"
+        thinking, clean = extract_think(text)
+        assert thinking == "reasoning content\nhere"
+        assert clean == "Hello  World"
+
+    def test_single_thought_block(self):
+        text = "Hello <thought>reasoning content</thought> World"
+        thinking, clean = extract_think(text)
+        assert thinking == "reasoning content"
+        assert clean == "Hello  World"
+
+    def test_multiple_think_blocks(self):
+        text = "A<think>first</think>B<thought>second</thought>C"
+        thinking, clean = extract_think(text)
+        assert thinking == "first\n\nsecond"
+        assert clean == "ABC"
+
+    def test_think_only_no_content(self):
+        text = "<think>just thinking</think>"
+        thinking, clean = extract_think(text)
+        assert thinking == "just thinking"
+        assert clean == ""
+
+    def test_unclosed_think_not_extracted(self):
+        # Unclosed blocks at start are stripped but NOT extracted
+        text = "<think>unclosed thinking..."
+        thinking, clean = extract_think(text)
+        assert thinking is None
+        assert clean == ""
+
+    def test_empty_think_block(self):
+        text = "Hello <think></think> World"
+        thinking, clean = extract_think(text)
+        # Empty blocks result in empty string after strip
+        assert thinking == ""
+        assert clean == "Hello  World"
+
+    def test_think_with_whitespace_only(self):
+        text = "Hello <think>   \n World"
+        thinking, clean = extract_think(text)
+        assert thinking is None
+        assert clean == "Hello <think>   \n World"
+
+    def test_mixed_think_and_thought(self):
+        text = "Start<think>first reasoning</think>middle<thought>second reasoning</thought>End"
+        thinking, clean = extract_think(text)
+        assert thinking == "first reasoning\n\nsecond reasoning"
+        assert clean == "StartmiddleEnd"
+
+    def test_real_world_ollama_response(self):
+        text = """<think>
+The user is asking about Python list comprehensions.
+Let me explain the syntax and give examples.
+</think>
+
+List comprehensions in Python provide a concise way to create lists. Here's the syntax:
+
+```python
+[expression for item in iterable if condition]
+```
+
+For example:
+```python
+squares = [x**2 for x in range(10)]
+```"""
+        thinking, clean = extract_think(text)
+        assert "list comprehensions" in thinking.lower()
+        assert "Let me explain" in thinking
+        assert "List comprehensions in Python" in clean
+        assert "<think>" not in clean
+        assert "</think>" not in clean