appload: load a .lsp file from a path or the file picker (#1903)

* appload: load a .lsp file from a path or the file picker (#1820)

APPLOAD had no user interface: typed or chosen from Tools > Load Application it
started a command-line prompt instead of a file browser, and the JSON form did
not say which commands the file defined.

- The desktop's APPLOAD opens an rfd file browser filtered to .lsp, starting in
  the folder the last routine came from (kept in the preferences as lispDir).
  A cancelled picker is a no-op; the web (no native dialog) keeps the engine's
  name prompt.
- The JSON form `appload {path}` loads to the end, never opens a dialog and now
  returns `commands`, the `c:` commands the file defined; a non-.lsp path is
  refused and unreadable or unparsable files return an ordinary error.
- Tests: a synthetic .lsp in a temp folder loads by path and its command runs;
  the picker path, its cancelled answer and the remembered folder; refused,
  missing and broken files.

* appload: load a picked file interactively; keep path whitespace; web hint

Reviewer follow-ups on #1820:

- A picked file now loads through the interactive APPLOAD command (started
  and answered with the picked path, as a typed name is), so a routine it
  starts that calls getpoint or another get… waits for the user instead of
  receiving nil. JSON calls keep the blocking run.
- A JSON `path` is read as given: only a path of blanks is refused, so a
  relative name with leading or trailing spaces is not trimmed into another
  file.
- The web has no file system, so APPLOAD no longer asks for a file name it
  cannot read: it says to drop a .lsp file on the window, which loads the
  file's contents. The host declares this through Services::no_file_system.

Tests: a picked file whose load asks for a point waits for it; a relative
path in a folder whose name starts with a space loads; on a host without a
file system APPLOAD gives the drop hint instead of prompting.

---------

Co-authored-by: Brandon Thomas <echelon@gmail.com>

docs/autolisp.md

@@ -5,8 +5,13 @@ CADCraft runs AutoLISP routines (`.lsp` files). What is here and what is not yet
 
 ## Loading and running
 
-- **APPLOAD** (Tools > Load Application…, alias `AP`) asks for a `.lsp` file and runs it. Dropping
-  a `.lsp` file on the window does the same.
+- **APPLOAD** (Tools > Load Application…, alias `AP`) opens a file browser filtered to `.lsp`
+  files, starting in the folder the last one came from (kept in the preferences), and runs the
+  chosen file. Cancelling the browser does nothing. A picked file loads as a typed name does, so a
+  routine it starts that asks for a point waits for it. A desktop without a file browser asks for
+  the name on the command line; the web has no file system, so it says to drop the `.lsp` file on
+  the window and loads it from its contents. Only `.lsp` files are loaded; anything else is
+  refused.
 - **`(load "name")`** loads a file by path, with `.lsp` added when the name has none. A file
   APPLOAD loaded is found again by its name, also on the web where there is no file system.
 - **`(defun c:NAME …)`** defines a command: type `NAME` at the command line. Built-in commands
@@ -16,8 +21,9 @@ CADCraft runs AutoLISP routines (`.lsp` files). What is here and what is not yet
   `CIRCLE 0,0 (* 2 r)`.
 - **Programmatically** (scripts, the control channel, MCP, the CLI): `lisp {code, inputs?}` and
   `appload {path} | {name, text | data}` run to the end and return `{value, output, error?}`.
-  `inputs` answer `get…` calls in order (numbers, strings, `[x, y]` points); a call with none left
-  gets nil.
+  `appload` also returns `commands`, the `c:` commands the file defined, and a JSON call never
+  opens a file dialog. `inputs` answer `get…` calls in order (numbers, strings, `[x, y]` points);
+  a call with none left gets nil.
 
 ### At startup
 

docs/gaps.md

@@ -133,7 +133,7 @@ Detail: [localization-parity.md](localization-parity.md).
 
 | # | Gap | Est. |
 |---|---|---|
-| E1 | AutoLISP beyond the core (#758 landed the language, `command`, entity lists, selection sets, `get…` input, APPLOAD, `(load)`, `c:` commands and `acad.lsp`/`acaddoc.lsp` at startup): Visual LISP ActiveX (`vlax-`, `vla-`), DCL dialogs, reactors, an APPLOAD dialog with a Startup Suite, UCS-aware `trans` | 30–50 |
+| E1 | AutoLISP beyond the core (#758 landed the language, `command`, entity lists, selection sets, `get…` input, APPLOAD, `(load)`, `c:` commands and `acad.lsp`/`acaddoc.lsp` at startup; #1820 gave APPLOAD its `.lsp` file picker): Visual LISP ActiveX (`vlax-`, `vla-`), DCL dialogs, reactors, an APPLOAD Startup Suite, UCS-aware `trans` | 26–46 |
 | E3 | Express Tools equivalents (SUPERHATCH; NCOPY, BREAKLINE, TXT2MTXT, BURST and MOCORO exist: BREAKLINE's Block option takes a block of the drawing, not a `.dwg` file, and TXT2MTXT's Settings are command-line prompts rather than a dialog, without the uniform line spacing option) | 24–40 |
 | E4 | Plug-in API (owner decision: Rust/WASM plug-ins rather than ObjectARX/.NET) | 30–50 |
 | E5 | CUI customisation (the alias editor, ALIASEDIT's Command Aliases dialog, landed, #1381; edits stay for the session) | 13–23 |
@@ -150,6 +150,7 @@ Detail: [localization-parity.md](localization-parity.md).
 
 | Date | Change | Summary |
 |---|---|---|
+| 2026-10-22 | minor | APPLOAD typed or from Tools ▸ Load Application opens a `.lsp` file browser starting in the last-used folder (kept in the preferences); a picked file loads interactively like a typed name (routines that ask for input wait), the web says to drop the file (no file system), and the JSON form `{path}` reads the path as given and returns the commands the file defined, never opening a dialog (#1820): E1 narrowed |
 | 2026-10-16 | minor | ALIASEDIT typed or from Tools ▸ Customize opens the Command Aliases dialog (user aliases next to the built-in ones; Add, Edit, Remove; OK, Cancel, Apply), #1381: U12 and E5 narrowed |
 | 2026-10-16 | minor | MOCORO (Tools ▸ Express Tools ▸ Move/Copy/Rotate): select objects and a base point once, then Move, Copy, Rotate, Scale, Base and Undo until eXit, one undo step; JSON form `{base, ops}`: E3 narrowed |
 | 2026-10-16 | minor | MLEDIT Merged Tee (MT): the first multiline's outer elements stop at the second one's near side, which opens, and its inner elements run on to the second one's inner element: F21 narrowed, hours unchanged |