fix: complete B-03/B-08/B-09 and add OMBRE_*_MODEL env vars

- decay_engine: keep activation_count as float (B-03);
  refresh local meta after auto_resolve so resolved_factor
  applies in the same cycle (B-08)
- server.hold(): user-supplied valence/arousal now takes
  priority over analyze() output (B-09)
- utils.load_config: support OMBRE_DEHYDRATION_MODEL
  (with OMBRE_MODEL alias) and OMBRE_EMBEDDING_MODEL
- ENV_VARS.md: document new model env vars
- tests/conftest.py: align fixture with spec-correct weights
  (time_proximity=1.5, content_weight=1.0) and feel subdir layout

ENV_VARS.md

@@ -9,6 +9,9 @@
 | `OMBRE_HOOK_URL` | 否 | — | Breath/Dream Webhook 回调地址，留空则不推送 |
 | `OMBRE_HOOK_SKIP` | 否 | `false` | 设为 `true` 跳过 Webhook 推送 |
 | `OMBRE_DASHBOARD_PASSWORD` | 否 | — | 预设 Dashboard 访问密码；设置后覆盖文件存储的密码，首次访问不弹设置向导 |
+| `OMBRE_DEHYDRATION_MODEL` | 否 | `deepseek-chat` | 脱水/打标/合并/拆分用的 LLM 模型名（覆盖 `dehydration.model`） |
+| `OMBRE_MODEL` | 否 | — | `OMBRE_DEHYDRATION_MODEL` 的别名（前者优先） |
+| `OMBRE_EMBEDDING_MODEL` | 否 | `gemini-embedding-001` | 向量嵌入模型名（覆盖 `embedding.model`） |
 
 ## 说明