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/index.md

@@ -1,6 +1,6 @@
 # Research Wiki 索引
 
-> 自动生成，更新时间：2026-08-02 09:38 UTC
+> 自动生成，更新时间：2026-08-02 09:49 UTC
 
 ## design (21)
 - [2026-07-20-m1-core-design](designs/2026-07-20-m1-core-design.md) `design:2026-07-20-m1-core-design`
@@ -39,7 +39,7 @@
 - [P7 OCR soak 验收: 99.73% 与 13 不变量全 PASS](findings/p7-ocr-soak.md) `finding:p7-ocr-soak`
 - [推理开关与 reasoning_tokens: 供应商实测与业界做法](findings/2026-08-02-thinking-switch-and-reasoning-tokens.md) `finding:2026-08-02-thinking-switch-and-reasoning-tokens`
 
-## plan (16)
+## plan (17)
 - [2026-07-20-m1-core-plan](plans/2026-07-20-m1-core-plan.md) `plan:2026-07-20-m1-core-plan`
 - [2026-07-20-m2-distributed-plan](plans/2026-07-20-m2-distributed-plan.md) `plan:2026-07-20-m2-distributed-plan`
 - [2026-07-21-m25-resilience-plan](plans/2026-07-21-m25-resilience-plan.md) `plan:2026-07-21-m25-resilience-plan`
@@ -55,6 +55,7 @@
 - [M3 OCR 实现计划](plans/m3-ocr.md) `plan:m3-ocr`
 - [M4 迁移实现计划(T0-T14)](plans/m4-migration.md) `plan:m4-migration`
 - [响应可观测字段扩展实现计划](plans/response-observability-fields.md) `plan:response-observability-fields`
+- [推理开关能力建模与 reasoning_tokens 采集实施计划(issue #5 + #6)](plans/2026-08-02-thinking-capability.md) `plan:2026-08-02-thinking-capability`
 - [采样参数透传实现计划(issue #4)](plans/sampling-params-plan.md) `plan:sampling-params-plan`
 
 ## schema (1)