Report prescan errors on their source lines

CLAUDE.md

@@ -26,7 +26,7 @@ scripting engine for game authors.
 | [the issue tracker](https://source.starfort.tech/andrew/akbasic/issues) | **Outstanding defects and gaps.** Labelled by kind and blast radius; `status::grooming` means the scope is not settled yet |
 | [`TODO.md`](TODO.md) | The record: settled design decisions, the deviation register, defects already fixed, and the reasoning behind the measurements. §0.1 first — it retires the byte-for-byte fidelity constraint several later sections were written on |
 | [`README.md`](README.md) | What the project is and why, for somebody who has not seen it |
-| [`docs/`](docs/README.md) | The language itself: twenty-one chapters, verb and function reference. [Chapter 14](docs/14-architecture.md) is the interpreter's architecture — the step loop, the pools, the two kinds of error, and how to debug it. [Chapter 15](docs/15-error-codes.md) is the error-code appendix. [Chapters 17](docs/17-tutorial-breakout.md) and [18](docs/18-tutorial-breakout-artwork.md) are tutorials that build the games in `examples/breakout/`; [Chapters 20](docs/20-tutorial-galaga.md) and [21](docs/21-tutorial-galaga-enemies.md) build the embedding host in `examples/galaga/` |
+| [`docs/`](docs/README.md) | The language itself: eighteen chapters, verb and function reference. [Chapter 14](docs/14-architecture.md) is the interpreter's architecture — the step loop, the pools, the two kinds of error, and how to debug it. [Chapter 15](docs/15-error-codes.md) is the error-code appendix. [Chapters 17](docs/17-tutorial-breakout.md) and [18](docs/18-tutorial-breakout-artwork.md) are tutorials that build the games in `examples/breakout/` |
 | `deps/libakerror/AGENTS.md` | The `ATTEMPT`/`CLEANUP`/`PROCESS`/`HANDLE`/`FINISH` protocol, authoritatively |
 | `deps/libakerror/UPGRADING.md` | 1.0.0's status registry. Required before writing an error code |
 | `deps/<library>/AGENTS.md` | Per-repo rules. Read the relevant one **before editing a submodule** |

CMakeLists.txt

@@ -268,69 +268,6 @@ if(AKBASIC_BUILD_EXAMPLES)
   endforeach()
 endif()
 
-# The galaga example: a C game on libakgl with the interpreter embedded as its
-# enemy-behavior engine. Chapters 20 and 21 build it from an empty file, so it
-# is compiled and run by every AKGL build rather than rotting in a document.
-# The asset, script and font paths are baked in so the smoke test can launch
-# from any working directory; --assets and --script override them at runtime.
-if(AKBASIC_BUILD_EXAMPLES AND AKBASIC_WITH_AKGL)
-  add_executable(akbasic_example_galaga
-    examples/galaga/main.c
-    examples/galaga/script.c
-    examples/galaga/enemies.c
-    examples/galaga/player.c)