docs: add implementation plan for thinking capability and reasoning tokens

Ten tasks in a fixed order: land reasoning_tokens first so it can serve
as the acceptance instrument for the thinking-switch fix, then reshape
the provider profile, add the model-level capability table, wire the
assembly guard, fold enable_thinking into the cache fingerprint, and
verify the whole thing against the live API.

Incorporates a read-only Codex review: resolve_thinking now takes the
model name so its errors can name it, and the warning assertion uses a
loguru sink because caplog cannot see loguru output.

research-wiki/graph/edges.json

@@ -230,6 +230,13 @@
       "relation": "supports",
       "evidence": "供应商实测与业界调研为该设计的形态/能力分层与失败语义提供事实依据",
       "added": "2026-08-02T09:38:57.033054+00:00"
+    },
+    {
+      "source": "plan:2026-08-02-thinking-capability",
+      "target": "design:2026-08-02-thinking-capability-design",
+      "relation": "implements",
+      "evidence": "T1-T10 逐条实现设计的 D1-D6 六个决策与 §11 九条验收标准",
+      "added": "2026-08-02T09:49:48.126539+00:00"
     }
   ]
 }