docs(security): reflect post-Light-Heart-Labs#988 host-agent fallback in SECURITY.md

Maintainer audit on PR Light-Heart-Labs#973 (Lightheartdevs, 2026-04-28):

  "Audit follow-up: needs rebase/update after the security merges.
   Light-Heart-Labs#988 is now on `main`, so docs should describe the safer loopback
   fallback behavior rather than the old exposure story. Please rebase
   this broad docs pass on current `main`, reconcile it with Light-Heart-Labs#988/Light-Heart-Labs#959,
   and make sure the host-agent/native binding sections consistently
   say `127.0.0.1` where that is now the implementation."

Light-Heart-Labs#988 (`fix/security-loopback`) changed `bin/dream-host-agent.py:2315`
to fall back to `127.0.0.1` instead of `0.0.0.0` when Docker bridge
detection fails. The "Host Agent Network Binding" table introduced
in this PR (commit `4ef9133c`) described pre-Light-Heart-Labs#988 behavior in the
Linux row. This commit corrects the cell with a parenthetical
pointing at Light-Heart-Labs#988 so the rationale isn't lost on future readers.

The other entries in the table (macOS/Windows already loopback,
override examples, bind-to-LAN warning) are unchanged.

Light-Heart-Labs#959-related changes: the token-spy proxy/upstream auth split is
already correctly captured by extension manifests + service
documentation that landed with Light-Heart-Labs#959; this PR's diff doesn't touch
those paths.

Closes the binding-doc audit ask. Branch is now rebased on current
upstream/main; rest of the docs sync (Qwen3.5/3 model names,
Windows-quickstart rewrite, FAQ expansions, langfuse README, etc.)
stands as before.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: yasinBursali

dream-server/SECURITY.md

@@ -84,7 +84,7 @@ The host agent (`bin/dream-host-agent.py`) has its own bind address, separate fr
 | Platform | Default | Behavior |
 |----------|---------|----------|
 | macOS / Windows | `127.0.0.1` | Docker Desktop routes container traffic via loopback — loopback is sufficient |
-| Linux | auto-detected | Detects the Docker bridge gateway IP (e.g. `172.17.0.1`) so containers can reach the agent; LAN devices cannot. Falls back to `0.0.0.0` if detection fails. |
+| Linux | auto-detected | Detects the Docker bridge gateway IP (e.g. `172.17.0.1`) so containers can reach the agent; LAN devices cannot. Falls back to `127.0.0.1` if detection fails (since #988 — the prior `0.0.0.0` fallback exposed the agent to LAN unnecessarily). |
 
 To override the default, set `DREAM_AGENT_BIND` in `.env`: