Make RustRaptor the repository root and track its playable bundle

docs/standalone-package.md

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+# Standalone Linux package
+
+`RustRaptor/` contains the Rust executable, its original data catalog, approved
+HD replacements, authored mods, SD/HD mod artwork, sound effects and music.
+Normal play needs no C++ engine, Cargo, Python or source checkout. Run
+`./run.sh`; installed pilots and configuration remain in the user's separate
+`RaptorReplica` profile directories.
+
+The executable finds its package from `bin/raptor-rust`, including when launched
+from another working directory. A missing packaged catalog reports an error
+instead of selecting another checkout's data. `--data` and `--mods` remain
+available for deliberate overrides.
+
+From this folder, run:
+
+```sh
+python3 tools/assemble_runtime.py --zip dist/RustRaptor-linux-x86_64.zip
+```
+
+The assembler builds the desktop release, copies all catalog-listed files and
+the exact currently approved HD manifest and referenced PNGs, installs the
+binary and SDL2 shared library if linked, and checks the packaged catalog.
+`runtime-manifest.json` records file hashes, catalog/HD counts and platform
+dependencies. Unapproved HD drafts, reference screenshots and the Cargo build
+cache are excluded from the zip. The exported `RustRaptor` folder can be moved
+or unpacked anywhere, including paths containing spaces.
+
+The binary targets Linux x86_64. It still uses the operating system's C runtime
+and desktop/audio drivers; this package is not a Windows or macOS executable.
+Source, Cargo.lock, code licenses and mod API documentation are included.
+The packaged executable, runtime libraries, original catalog and approved HD
+artwork are tracked in Git, along with the assembler and authored mod images
+and sounds. Build caches, working art drafts, review evidence and duplicate zip
+exports are excluded. See [repository layout](repository.md).
+
+Re-run the assembler after engine changes, new approved HD registrations or
+mod edits to refresh the package. The runtime snapshot contains approved art
+only; it does not claim the full original HD catalog is complete.
+
+The current package was unpacked into a folder containing spaces and launched
+from `/tmp` with only its bundled SDL2 library on the library search path.
+Catalog validation checked 6,449 assets, 27 missions, 528 enemies, 16 weapons
+and 24 items. All 22 bundled mods and all 221 approved HD frames validated.
+Menu and gameplay screenshots at 1280×800 and 1920×1080, plus stereo audio
+captures, completed successfully. Native `unzip` preserves the executable
+permissions stored in the archive.
+An original-intro capture at 1080p also confirms a 1440×1080 video area and
+black 240-pixel side borders when gameplay stretching is enabled. Removing
+the copied catalog produces an error at the copied data path, with no fallback
+to the development checkout.