feat: multimodal image clients, workspaces, Tushare skill, test fixes

- Replace monolithic image_message_client with HTTP/OCR/legacy modules; tighten OpenAI transport + tool schemas for multimodal downgrade to OCR specialist path.
- Add image/stock workspace prompts (META/SOUL/ROLE_SYSTEM); register experts; tweak specialist agent/direct loop/query_image_attachment.
- Add bundled runtime/skills/tushare-finance (references, api_client, SKILL metadata).
- Document OCR-related env vars; admin chat tweaks; README; weixin_install Ensure-OfficialPluginRuntimeDeps helper.
- Tests: multimodal downgrade + OCR coverage, strict tool pairing in attachment replay guard, workspace contract skips _internal/_system dirs, router/trace/prompt guards.

Co-authored-by: Cursor <cursoragent@cursor.com>

runtime/workspaces/experts.py

@@ -252,7 +252,7 @@ def build_expert_catalog_block(*, include_main: bool = False, per_field_limit: i
 
 def discover_specialist_ids_from_workspaces(
     *,
-    base_order: tuple[str, ...] = ("generalist", "ops", "memory"),
+    base_order: tuple[str, ...] = ("generalist", "ops", "memory", "image"),
 ) -> tuple[str, ...]:
     cache_key = (expert_workspace_signature_token(), tuple(str(x).strip().lower() for x in base_order if str(x).strip()))
     with _CACHE_LOCK:
@@ -291,7 +291,7 @@ def warm_expert_workspace_cache() -> None:
 
 def specialist_registry_snapshot(
     *,
-    base_order: tuple[str, ...] = ("generalist", "ops", "memory"),
+    base_order: tuple[str, ...] = ("generalist", "ops", "memory", "image"),
 ) -> tuple[dict[str, Any], ...]:
     """Single source of truth for runtime specialist discovery and metadata."""
     ordered = discover_specialist_ids_from_workspaces(base_order=base_order)