docs: tighten architecture, btw, agent-send hygiene

docs/concepts/architecture.md: replaced 8 non-breaking hyphen
characters (U+2011) with regular hyphens. Non-breaking hyphens defeat
copy-paste from rendered HTML, break grep on the raw markdown, and
make Mintlify search miss otherwise-correct queries. Affected words:
'long-lived', 'server-push', 'device-based'.

docs/tools/btw.md: converted the 3-bullet Related list into a
CardGroup. Renamed 'Thinking Levels' to sentence-case 'Thinking
levels' and added a Steer-command card so readers comparing ephemeral
vs in-run intervention paths see both options.

docs/tools/agent-send.md: converted the 3-bullet Related list into a
CardGroup. Removed two em-dash characters in the bullet copy
('Sub-agents — background sub-agent spawning', 'Sessions — how
session keys work') and added a Slash-commands card. Verified
/cli/agent, /tools/subagents, /concepts/session, and
/tools/slash-commands targets all exist.

docs/concepts/architecture.md

@@ -7,7 +7,7 @@ title: "Gateway architecture"
 
 ## Overview
 
-- A single long‑lived **Gateway** owns all messaging surfaces (WhatsApp via
+- A single long-lived **Gateway** owns all messaging surfaces (WhatsApp via
   Baileys, Telegram via grammY, Slack, Discord, Signal, iMessage, WebChat).
 - Control-plane clients (macOS app, CLI, web UI, automations) connect to the
   Gateway over **WebSocket** on the configured bind host (default
@@ -25,7 +25,7 @@ title: "Gateway architecture"
 ### Gateway (daemon)
 
 - Maintains provider connections.
-- Exposes a typed WS API (requests, responses, server‑push events).
+- Exposes a typed WS API (requests, responses, server-push events).
 - Validates inbound frames against JSON Schema.
 - Emits events like `agent`, `chat`, `presence`, `health`, `heartbeat`, `cron`.
 
@@ -38,7 +38,7 @@ title: "Gateway architecture"
 ### Nodes (macOS / iOS / Android / headless)
 
 - Connect to the **same WS server** with `role: node`.
-- Provide a device identity in `connect`; pairing is **device‑based** (role `node`) and
+- Provide a device identity in `connect`; pairing is **device-based** (role `node`) and
   approval lives in the device pairing store.
 - Expose commands like `canvas.*`, `camera.*`, `screen.record`, `location.get`.
 
@@ -90,8 +90,8 @@ sequenceDiagram
   instead of `connect.params.auth.*`.
 - Private-ingress `gateway.auth.mode: "none"` disables shared-secret auth
   entirely; keep that mode off public/untrusted ingress.
-- Idempotency keys are required for side‑effecting methods (`send`, `agent`) to
-  safely retry; the server keeps a short‑lived dedupe cache.
+- Idempotency keys are required for side-effecting methods (`send`, `agent`) to
+  safely retry; the server keeps a short-lived dedupe cache.
 - Nodes must include `role: "node"` plus caps/commands/permissions in `connect`.
 
 ## Pairing + local trust
@@ -109,7 +109,7 @@ sequenceDiagram
 - Signature payload `v3` also binds `platform` + `deviceFamily`; the gateway
   pins paired metadata on reconnect and requires repair pairing for metadata
   changes.
-- **Non‑local** connects still require explicit approval.
+- **Non-local** connects still require explicit approval.
 - Gateway auth (`gateway.auth.*`) still applies to **all** connections, local or
   remote.
 
@@ -138,12 +138,12 @@ Details: [Gateway protocol](/gateway/protocol), [Pairing](/channels/pairing),
 
 - Start: `openclaw gateway` (foreground, logs to stdout).
 - Health: `health` over WS (also included in `hello-ok`).
-- Supervision: launchd/systemd for auto‑restart.
+- Supervision: launchd/systemd for auto-restart.
 
 ## Invariants
 
 - Exactly one Gateway controls a single Baileys session per host.
-- Handshake is mandatory; any non‑JSON or non‑connect first frame is a hard close.
+- Handshake is mandatory; any non-JSON or non-connect first frame is a hard close.
 - Events are not replayed; clients must refresh on gaps.
 
 ## Related

docs/tools/agent-send.md

@@ -93,6 +93,17 @@ openclaw agent --agent ops --message "Alert" --deliver --reply-channel telegram
 
 ## Related
 
-- [Agent CLI reference](/cli/agent)
-- [Sub-agents](/tools/subagents) — background sub-agent spawning
-- [Sessions](/concepts/session) — how session keys work
+<CardGroup cols={2}>
+  <Card title="Agent CLI reference" href="/cli/agent" icon="terminal">
+    Full `openclaw agent` flag and option reference.
+  </Card>
+  <Card title="Sub-agents" href="/tools/subagents" icon="users">
+    Background sub-agent spawning.
+  </Card>
+  <Card title="Sessions" href="/concepts/session" icon="comments">
+    How session keys work and how `--to`, `--agent`, and `--session-id` resolve them.
+  </Card>
+  <Card title="Slash commands" href="/tools/slash-commands" icon="slash">
+    Native command catalog used inside agent sessions.
+  </Card>
+</CardGroup>

docs/tools/btw.md

@@ -136,6 +136,17 @@ In that case, ask normally in the main session instead of using BTW.
 
 ## Related
 
-- [Slash commands](/tools/slash-commands)
-- [Thinking Levels](/tools/thinking)
-- [Session](/concepts/session)
+<CardGroup cols={2}>
+  <Card title="Slash commands" href="/tools/slash-commands" icon="terminal">
+    Native command catalog and chat directives.
+  </Card>
+  <Card title="Thinking levels" href="/tools/thinking" icon="brain">
+    Reasoning effort levels for the side-question model call.
+  </Card>
+  <Card title="Session" href="/concepts/session" icon="comments">
+    Session keys, history, and persistence semantics.
+  </Card>
+  <Card title="Steer command" href="/tools/steer" icon="arrow-right">
+    Inject a steering message into the active run without ending it.
+  </Card>
+</CardGroup>