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/extensions/developing-extensions.md

@@ -1,8 +1,15 @@
-# Developing Extensions
+---
+title: Developing Extensions
+description: "Create Zed extensions: languages, themes, debuggers, slash commands, and more."
+---
 
-## Extension Features
+# Developing Extensions {#developing-extensions}
 
-Extensions are able to provide the following features to Zed:
+Zed extensions are Git repositories containing an `extension.toml` manifest. They can provide languages, themes, debuggers, slash commands, and MCP servers.
+
+## Extension Features {#extension-features}
+
+Extensions can provide:
 
 - [Languages](./languages.md)
 - [Debuggers](./debugger-extensions.md)
@@ -21,7 +28,7 @@ When developing an extension, you can use it in Zed without needing to publish i
 
 From the extensions page, click the `Install Dev Extension` button (or the {#action zed::InstallDevExtension} action) and select the directory containing your extension.
 
-If you need to troubleshoot, you can check the Zed.log ({#action zed::OpenLog}) for additional output. For debug output, close and relaunch zed with the `zed --foreground` from the command line which show more verbose INFO level logging.
+If you need to troubleshoot, check Zed.log ({#action zed::OpenLog}) for additional output. For debug output, close and relaunch Zed from the command line with `zed --foreground`, which shows more verbose INFO-level logs.
 
 If you already have the published version of the extension installed, the published version will be uninstalled prior to the installation of the dev extension. After successful installation, the `Extensions` page will indicate that the upstream extension is "Overridden by dev extension".
 
@@ -36,11 +43,11 @@ name = "My extension"
 version = "0.0.1"
 schema_version = 1
 authors = ["Your Name <you@example.com>"]
-description = "My cool extension"
+description = "Example extension"
 repository = "https://github.com/your-name/my-zed-extension"
 ```
 
-> Note: If you are working on a theme extension with the intend of publishing it later, is is recommended that you suffix your theme's extension ID with `-theme`. This might otherwise be raised during the process of [releasing your extension](#publishing-your-extension).
+> **Note:** If you are working on a theme extension with the intent to publish it later, suffix your theme extension ID with `-theme`. Otherwise, this may be raised during [extension publishing](#publishing-your-extension).
 
 In addition to this, there are several other optional files and directories that can be used to add functionality to a Zed extension. An example directory structure of an extension that provides all capabilities is as follows:
 
@@ -99,7 +106,7 @@ zed::register_extension!(MyExtension);
 
 1. Fork the repo
 
-> Note: It is very helpful if you fork the `zed-industries/extensions` repo to a personal GitHub account instead of a GitHub organization, as this allows Zed staff to push any needed changes to your PR to expedite the publishing process.
+> **Note:** It is very helpful if you fork the `zed-industries/extensions` repo to a personal GitHub account instead of a GitHub organization, as this allows Zed staff to push any needed changes to your PR to expedite the publishing process.
 
 2. Clone the repo to your local machine