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.

dockerfile.unified

@@ -6,6 +6,7 @@
 FROM node:20-bookworm AS base
 
 # Re-declare build arguments after FROM (ARGs before FROM are not available after)
+ARG APP_VERSION=unknown
 ARG GIT_COMMIT=unknown
 ARG BUILD_DATE=unknown
 
@@ -51,9 +52,11 @@ ENV DATABASE_URL="postgresql://dummy:dummy@localhost:5432/dummy?schema=public"
 RUN npx prisma generate
 
 # Set version environment variables for build and runtime
+ENV NEXT_PUBLIC_APP_VERSION=${APP_VERSION}
 ENV NEXT_PUBLIC_GIT_COMMIT=${GIT_COMMIT}
 ENV NEXT_PUBLIC_BUILD_DATE=${BUILD_DATE}
-ENV APP_VERSION=${GIT_COMMIT}
+ENV APP_VERSION=${APP_VERSION}
+ENV GIT_COMMIT=${GIT_COMMIT}
 ENV BUILD_DATE=${BUILD_DATE}
 
 # Build Next.js application