#759: #include / //@include / #includepath in scripts

Problem: ExtendScript's preprocessor directives weren't understood, so a
script (or ScriptUI panel, or library such as DuAEF) failed to parse at
its first `#include`; `#target` / `#targetengine` / `#strict` lines broke
parsing too.

Fix: before a script runs, `include::expand` inlines `#include "f"` and
`//@include "f"` in place of the line, resolved against the including
file's folder, then the folders of the latest `#includepath "a;b"`.
Each file is inlined once (which also breaks cycles), nesting is limited
to 32, files are capped at 16 MiB (64 MiB in all), and reads follow the
scripts' file gate (the script's own folder, the project's folder, or
anywhere with Allow Scripts to Write Files). `#target`, `#targetengine`,
`#strict`, `#script` and `#engine` are dropped. Errors in the expanded
code are mapped back to the included file and its line. Scripts without
directives run unchanged. File resolution, the gate and the limits live
in `scriptfile.rs` for `$.evalFile` (#760) to share.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

docs/scripting-parity.md

@@ -22,7 +22,7 @@ our own scripts; no real-world script library has been run against both apps.
 | ScriptUI | Dialogs, palettes, dockable panels, resource strings, `onDraw` / ScriptUIGraphics | Same, dockable panels reopen at launch | good | `ui_scriptui`, `tests_ui*` |
 | Scripts menu, ScriptUI Panels folder | yes | yes | same | [plugins.md](plugins.md) |
 | Startup / Shutdown folders | yes | not run | missing | plugins.md |
-| `#include`, `#target` directives | yes | a script starting with one doesn't parse | missing | plugins.md; common in real scripts |
+| `#include`, `#target` directives | yes | `#include` / `//@include` / `#includepath` inline files relative to the including script (once each, nested at most 32 deep, under the scripts' file gate; errors name the included file and line); `#target`, `#targetengine`, `#strict` are ignored | good | `tests_include.rs` (#759); installed scripts and panels have no folder of their own, so they include from the project's folder or absolute paths |
 | `.jsxbin` | yes | no | out of scope | No public specification |
 | Keyboard shortcuts for scripts | yes | no | missing | plugins.md |
 | Command-line rendering `aerender` | yes | `effectcraft-cli render`, `script`, `exec` | same purpose | `apps/effectcraft-cli` |