Restructure docs navigation: CLI section, Composition, More (#3361)

* WIP: Move mounting docs to servers/composition, remove deprecated import_server content

* WIP: Add CLI section under More, move testing to Features, restructure nav

* WIP: Rename querying to client, remove factory functions from CLI overview

* WIP: Promote CLI to top-level section, move Upgrading to More

* WIP: Rename CLI installing page to install-mcp

* WIP

* Add Google Gemini sampling handler docs, fix version badges

docs/development/v3-notes/v3-features.mdx

@@ -185,7 +185,7 @@ Key features:
 - Fuzzy tool name matching suggests alternatives on typos
 - Interactive terminal elicitation for tools that request user input mid-execution
 
-Documentation: [Client CLI](/clients/cli)
+Documentation: [CLI Querying](/cli/client)
 
 ### CLI: `fastmcp discover` and name-based resolution
 
@@ -207,7 +207,7 @@ fastmcp call cursor:weather get_forecast city=London
 fastmcp discover --source claude-code --source cursor
 ```
 
-Documentation: [Client CLI](/clients/cli)
+Documentation: [CLI Querying](/cli/client)
 
 ### CLI: Expanded Reload File Watching
 
@@ -315,7 +315,7 @@ python my_weather_cli.py read-resource docs://readme
 
 The generated script embeds the resolved transport (URL or stdio command), so it's self-contained — users don't need to know about MCP or FastMCP to use it. Supports `-f` to overwrite existing files, and name-based resolution via `fastmcp discover`.
 
-Documentation: [Generate CLI](/clients/generate-cli)
+Documentation: [Generate CLI](/cli/generate-cli)
 
 ### CLI: Goose Integration