Synchronize Devvit documentation with current behavior

[CR29-22-2805]

Summary

Several Devvit documentation pages no longer match the current configuration schema, CLI, or Devvit Web APIs. Some discrepancies can cause developers to copy invalid configuration, use unsupported commands, or rely on deprecated examples.

Issues

• The documented server entry path resolves incorrectly with the default server directory.
• The app-name limit and default post height do not match the schema.
• Several supported devvit.json fields are missing from the configuration guide.
• The CLI guide documents outdated syntax, a nonexistent --here option, and a nonexistent devvit build command.
• devvit publish and several current CLI options are undocumented.
• The launch-screen guide recommends deprecated web-view mode listeners and misstates the expanded-mode event contract.
• Redis documentation links to old 0.12 files and contains a malformed code example.
• The latest documentation version is duplicated in docusaurus.config.ts instead of being derived from versions.json.

Proposed changes

• Synchronize the configuration and CLI guides with the current implementation.
• Replace deprecated launch-screen examples.
• Correct stale links, malformed examples, and minor navigation errors.
• Apply equivalent changes to both docs/ and versioned_docs/version-0.13/.
• Derive the latest published documentation version from versions.json.

Out of scope

This issue does not cover the modern generated Reddit API reference, source-level JSDoc changes, Blob Storage permission behavior, or subscription identity API changes.