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/log.md

@@ -78,3 +78,7 @@
 - [2026-08-02 09:38 UTC] 新增 finding: 推理开关与 reasoning_tokens 供应商实测与业界做法 (finding:2026-08-02-thinking-switch-and-reasoning-tokens)
 - [2026-08-02 09:38 UTC] 新增 design: 推理开关能力建模与 reasoning_tokens 采集 issue #5+#6 (design:2026-08-02-thinking-capability-design)
 - [2026-08-02 09:39 UTC] 重建 Query Pack: 29 字符
+- [2026-08-02 09:49 UTC] 重建索引: 53 篇页面
+- [2026-08-02 09:49 UTC] 新增边: plan:2026-08-02-thinking-capability --implements--> design:2026-08-02-thinking-capability-design
+- [2026-08-02 09:49 UTC] 新增 plan: 推理开关能力建模与 reasoning_tokens 采集实施计划 (plan:2026-08-02-thinking-capability)
+- [2026-08-02 09:49 UTC] 重建索引: 53 篇页面