Add admin-unlimited workspaces, AI gateway model fallback, and real streaming/thinking control

Admin-unlimited Dev Workspaces: an admin-owned workspace is now exempt from the
max-workspace-count limit, the max-tunnel-count limit, and the whole
idle-stop/idle-warn/retention-delete lifecycle. Resolved once in
quota.resolve() as Limits.unlimited (owner uid checked against
get_admin_uids()), consumed at the three enforcement points
(provision.ensure, provision.publish_tunnel,
WorkspaceService._advance_lifecycle). Also hardens
get_admin_uids()/get_primary_admin_uid() against a partially-schemaed users
table (uid/role column guard), which a fresh test/init_db() path could hit.

AI gateway per-model automatic fallback: any gateway_models route
(chat/embed/image) can now name a fallback_model, picked on /admin/gateway
from a select box of other configured public model names of the same kind
only (never an internal upstream model id). When a route fails after its own
retries are exhausted, the gateway retries once, automatically, against the
fallback's own provider/pricing/key, before any bytes reach the client
(including for a streaming response). One hop only, no chains or cycles;
self-reference and cross-kind fallbacks are rejected at write time.

AI gateway real upstream streaming and thinking-default control: stream:true
is now forwarded to the upstream and relayed to the client as real SSE
chunks (measured TTFT/inter-token latency) instead of a simulated split
response, and every chat/vision call explicitly disables model "thinking" by
default (admin-overridable via gateway_thinking), with per-dialect handling
for DeepSeek, OpenRouter, and Ollama.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TjdKTWgWpW2SMNW8SFqxz5

devplacepy/services/openai_gateway/service.py

@@ -120,6 +120,18 @@ class GatewayService(BaseService):
             "content, all in one system message). Leave blank to disable.",
             group="Prompt",
         ),
+        ConfigField(
+            "gateway_thinking",
+            "Enable thinking by default",
+            type="bool",
+            default=config.THINKING_DEFAULT,
+            help="Off by default: the gateway disables model thinking on every chat "
+            "call (DeepSeek thinking.type=disabled, OpenRouter reasoning.effort=none, "
+            "Ollama think=false) unless the client explicitly enables it with think, "
+            "thinking, or reasoning. Fastest path. On: thinking is enabled unless the "
+            "client disables it.",
+            group="Prompt",
+        ),
         ConfigField(
             "gateway_vision_enabled",
             "Vision augmentation",