docs: fix stale references across 8 doc pages

Audit found 24+ discrepancies between docs and code. Fixed:

HIGH severity:
- Remove honcho toolset from tools-reference, toolsets-reference, and tools.md
  (converted to memory provider plugin, not a built-in toolset)
- Add note that Honcho is available via plugin

MEDIUM severity:
- Add hermes memory command family to cli-commands.md (setup/status/off)
- Add --clone-all, --clone-from to profile create in cli-commands.md
- Add --max-turns option to hermes chat in cli-commands.md
- Add /btw slash command to slash-commands.md
- Fix profile show example output (remove nonexistent disk usage,
  add .env and SOUL.md status lines)
- Add missing hermes-webhook toolset to toolsets-reference.md
- Add 5 missing providers to fallback-providers.md table
- Add 7 missing providers to providers.md fallback list
- Fix outdated model examples: glm-4-plus→glm-5, moonshot-v1-auto→kimi-for-coding

website/docs/reference/slash-commands.md

@@ -35,6 +35,7 @@ Type `/` in the CLI to open the autocomplete menu. Built-in commands are case-in
 | `/resume [name]` | Resume a previously-named session |
 | `/statusbar` (alias: `/sb`) | Toggle the context/model status bar on or off |
 | `/background <prompt>` (alias: `/bg`) | Run a prompt in a separate background session. The agent processes your prompt independently — your current session stays free for other work. Results appear as a panel when the task finishes. See [CLI Background Sessions](/docs/user-guide/cli#background-sessions). |
+| `/btw <question>` | Ephemeral side question using session context (no tools, not persisted). Useful for quick clarifications without affecting the conversation history. |
 | `/plan [request]` | Load the bundled `plan` skill to write a markdown plan instead of executing the work. Plans are saved under `.hermes/plans/` relative to the active workspace/backend working directory. |
 
 ### Configuration