docs: Apply documentation standards across all docs (#49177)

## Summary

Comprehensive remediation of 146 documentation files to align with Zed's
documentation conventions and brand voice guidelines.

## Changes

### YAML Frontmatter
- Added `title` and `description` frontmatter to all docs missing it

### Settings UI Pattern
- Updated 48+ files to show Settings Editor before JSON examples
- Pattern: `Configure X in Settings ({#kb zed::OpenSettings}), or add to
your settings file:`
- Added `([how to edit](./configuring-zed.md#settings-files))` links for
JSON-only settings

### Brand Voice Fixes
- Removed exclamation points (command-palette, key-bindings, repl,
privacy-and-security, etc.)
- Simplified em dash chains to parentheticals (environment,
troubleshooting, agent-panel, etc.)
- Fixed marketing language (yarn.md intro, development/linux.md)

### Terminology Alignment
- `settings UI` -> `Settings Editor`
- `sidebar` -> specific panel names (Project Panel, Collab Panel)
- `directory` -> `folder` in non-technical contexts
- `workspace` -> `project` in non-LSP contexts
- `Command Palette` -> `command palette` (lowercase)

### Callout Standardization
- Converted various callout formats to standard `> **Note:**` pattern

## Related

Depends on conventions established in #49176.

Release Notes:

- N/A

docs/src/vim.md

@@ -79,7 +79,7 @@ The following commands use the language server to help you navigate and refactor
 
 ### Tree-sitter
 
-Tree-sitter is a powerful tool that Zed uses to understand the structure of your code. Zed provides motions that change the current cursor position, and text objects that can be used as the target of actions.
+Tree-sitter is the parser Zed uses to understand the structure of your code. Zed provides motions that change the current cursor position, and text objects that can be used as the target of actions.
 
 | Command                         | Default Shortcut            |
 | ------------------------------- | --------------------------- |
@@ -155,7 +155,7 @@ The following commands help you bring up Zed's completion menu, request a sugges
 
 ### Supported plugins
 
-Zed's vim mode includes some features that are usually provided by very popular plugins in the Vim ecosystem:
+Zed's vim mode includes features commonly provided by plugins in the Vim ecosystem:
 
 - You can surround text objects with `ys` (yank surround), change surrounding with `cs`, and delete surrounding with `ds`.
 - You can comment and uncomment selections with `gc` in visual mode and `gcc` in normal mode.