Synchronize Devvit documentation with current behavior

[CR29-22-2805]

Closes #159

💸 TL;DR

This PR synchronizes Devvit’s configuration, CLI, launch-screen, and Redis documentation with the current implementation. It corrects invalid or outdated examples, documents additional supported configuration fields, and applies equivalent updates to both the current and versioned 0.13 documentation. It also centralizes the latest published documentation version through versions.json.

📜 Details

Design Doc: Not applicable

Jira: Not applicable

This documentation-only PR:

• Corrects the documented server build path, app-name limit, and default custom-post height.
• Expands the devvit.json reference to cover additional schema-supported settings, permissions, triggers, assets, payments, and server options.
• Updates CLI documentation for init, publish, logs, playtest, upload, and view.
• Removes references to the nonexistent devvit build command and --here option.
• Replaces deprecated launch-screen mode-listener examples with the current focus-based approach.
• Corrects stale Redis links and repairs a malformed transaction example.
• Removes a duplicated sidebar entry and fixes minor changelog errors.
• Derives LATEST_DEVVIT_VERSION from the first entry in versions.json rather than duplicating the version in docusaurus.config.ts.
• Mirrors applicable changes in both docs/ and versioned_docs/version-0.13/.

This PR does not change Devvit runtime behavior, generated API references, Blob Storage permission behavior, or Reddit subscription identity APIs.

🧪 Testing Steps / Validation

The following checks were completed against the current repository snapshot:

1. Applied the patch successfully with:

   git apply --check devvit-docs-patch-1-docs-sync.patch

2. Checked the resulting diff for whitespace errors:

   git diff --check

3. Parsed all JSON code blocks changed in the configuration guides.

4. Verified that relative documentation links in the changed files resolve.

5. Checked that Markdown code fences remain balanced.

6. Checked the changed documentation for unexpected control characters.

7. Confirmed that equivalent updates were made to the current and versioned 0.13 documentation where applicable.

A complete local Docusaurus build was not run because installed dependencies were not included in the supplied repository snapshot. Repository CI should run the full documentation build.

CI note: The Build Documentation workflow is currently marked action_required because this pull request originates from a fork. A repository maintainer must approve the workflow before the CI jobs can run. No CI failures have been reported at this stage.

✅ Checks

• CI tests (if present) are passing
• Adheres to code style for repo
• Contributor License Agreement (CLA) completed if not a Reddit employee