docs: batch fix filler Note/page openers and one TUI auth Warning

- gateway/authentication: tighten model-provider Note opener
- help/debugging: drop 'this page covers' filler
- reference/session-management-compaction: rephrase end-to-end intro
- reference/transcript-hygiene: drop 'this document describes' filler
- web/index: collapse 'this page focuses' filler
- web/tui: convert prose --url Note to Warning component

docs/web/index.md

@@ -12,8 +12,7 @@ The Gateway serves a small **browser Control UI** (Vite + Lit) from the same por
 - with `gateway.tls.enabled: true`: `https://<host>:18789/`
 - optional prefix: set `gateway.controlUi.basePath` (e.g. `/openclaw`)
 
-Capabilities live in [Control UI](/web/control-ui).
-This page focuses on bind modes, security, and web-facing surfaces.
+Capabilities live in [Control UI](/web/control-ui). The rest of this page focuses on bind modes, security, and web-facing surfaces.
 
 ## Webhooks