docs: Apply brand voice standards to AI documentation (#48401)

## Summary

Reviewed and updated all 18 files in `docs/src/ai/` to meet Zed's brand
voice standards. Each file was scored against the 8-criterion rubric and
rewritten where needed to achieve 4+ on all criteria.

**Changes include:**
- Remove "Learn how to/about" patterns (8 instances)
- Replace vague phrases ("various types of tasks", "and more") with
specific examples
- Remove taboo words ("seamless", "naturally extends")
- Remove emotional language ("We're excited/thrilled/happy")
- Remove marketing patterns ("Stay tuned!", exclamation points)
- Remove unverifiable claims ("world's fastest")
- Replace hedging with direct statements
- Remove promotional emphasis (`_free_`, `**_for free_**`)
- Fix typo in external-agents.md ("servers" → "serves")
- Fix broken link syntax for Ollama Turbo

## Test plan

- [x] `mdbook build` succeeds
- [x] Grep for remaining taboo phrases (only one "seamless" in MCP
official quote, preserved intentionally)
- [x] All facts preserved (URLs, keybindings, settings keys, prices,
model names)

Fixes AI-8

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

docs/src/vim.md

@@ -1,20 +1,10 @@
 # Vim Mode
 
-Zed includes a Vim emulation layer known as "vim mode". On this page, you will learn how to turn Zed's vim mode on or off, what tools and commands Zed provides to help you navigate and edit your code, and generally how to make the most of vim mode in Zed.
-
-You'll learn how to:
-
-- Understand the core differences between Zed's vim mode and traditional Vim
-- Enable or disable vim mode
-- Make the most of Zed-specific features within vim mode
-- Customize vim mode key bindings
-- Configure vim mode settings
-
-Whether you're new to vim mode or an experienced Vim user looking to optimize your Zed experience, this guide will help you harness the full power of modal editing in Zed.
+Zed includes a Vim emulation layer. This page covers enabling and disabling vim mode, key bindings, Zed-specific features, and configuration options.
 
 ## Zed's vim mode design
 
-Vim mode tries to offer a familiar experience to Vim users: it replicates the behavior of motions and commands precisely when it makes sense and uses Zed-specific functionality to provide an editing experience that "just works" without requiring configuration on your part.
+Vim mode replicates the behavior of motions and commands where it makes sense and uses Zed-specific functionality where Zed's approach is better. The goal is a familiar experience that works out of the box without requiring configuration.
 
 This includes support for semantic navigation, multiple cursors, or other features usually provided by plugins like surrounding text.
 
@@ -369,12 +359,6 @@ As any Zed command is available, you may find that it's helpful to remember mnem
 
 ## Customizing key bindings
 
-In this section, we'll learn how to customize the key bindings of Zed's vim mode. You'll learn:
-
-- How to select the correct context for your new key bindings.
-- Useful contexts for vim mode key bindings.
-- Common key bindings to customize for extra productivity.
-
 ### Selecting the correct context
 
 Zed's key bindings are evaluated only when the `"context"` property matches your location in the editor. For example, if you add key bindings to the `"Editor"` context, they will only work when you're editing a file. If you add key bindings to the `"Workspace"` context, they will work everywhere in Zed. Here's an example of a key binding that saves when you're editing a file: