Add volume mapping docs and build/version metadata

Add a volume-mapping guide and surface build/version metadata throughout the project.

Changes included:
- documentation: Add documentation/deployment/volume-mapping.md and update TABLEOFCONTENTS.md and README to reference it (helps users align download client and RMAB paths).
- CI: Capture package.json version in .github/workflows/build-unified-image.yml, pass APP_VERSION as a build-arg, and update the Discord notification to show the semantic version and pull `:latest`.
- Docker: Declare ARG APP_VERSION and expose NEXT_PUBLIC_APP_VERSION / APP_VERSION / GIT_COMMIT env vars in dockerfile.unified so runtime and client can read the semantic version and commit.
- App API/UI: Update src/app/api/version/route.ts and src/components/ui/VersionBadge.tsx to prefer semantic app version (APP_VERSION / NEXT_PUBLIC_APP_VERSION), include fullVersion and commit info, show commit in tooltip, and adjust fallback/dev labels.
- Tests: Update tests (system.routes.test.ts and VersionBadge.test.tsx) to reflect the new version/commit fields and behavior.
- Audible integration: Add ipRedirectOverride query param to multiple Audible requests to avoid IP-based region redirects.
- Misc: Bump package.json version to 1.0.0.

These changes make version information consistent between build, runtime, and UI, improve CI notifications, add user guidance for common volume-mapping issues, and harden Audible scraping against region redirects.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "readmeabook",
-  "version": "0.1.0",
+  "version": "1.0.0",
   "private": true,
   "scripts": {
     "dev": "next dev",