feat(v4.0.0): reading a line and splitting it into words and numbers

The first layer of the compiler capsule, on the host node: TIB >IN SPAN
SOURCE BL EXPECT QUERY WORD ENCLOSE CONVERT NUMBER and the comment
words.  The definitions are text, v4/capsule/core.v4 (the core words
they rest on) and v4/capsule/input.v4, assembled by the text assembler,
which can now read a file.

EXPECT, QUERY, WORD and ENCLOSE behave as v3's.  CONVERT and NUMBER are
FORTH-79 (ruled 2026-10-04): any BASE, a double in the standard order,
and NUMBER returns a signed double or sets NODE-ERROR.

Executed at both cell widths against C and against values recorded from
the v3 binary.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

v4/src/text.c

@@ -394,6 +394,35 @@ int v4_text_assemble(v4_text *t, const char *source)
     return !t->failed;
 }
 
+int v4_text_assemble_file(v4_text *t, const char *path)
+{
+    const char *base = strrchr(path, '/');
+    char *text = NULL, was[sizeof t->message];
+    long size = 0;
+    FILE *f;
+
+    if (t->failed) return 0;
+    base = base ? base + 1 : path;
+    f = fopen(path, "rb");
+    if (f && fseek(f, 0, SEEK_END) == 0 && (size = ftell(f)) >= 0 && fseek(f, 0, SEEK_SET) == 0)
+        text = malloc((size_t)size + 1u);
+    if (!text || fread(text, 1, (size_t)size, f) != (size_t)size) {
+        if (f) fclose(f);
+        free(text);
+        t->line = 0;
+        fail(t, "cannot read", path);
+        return 0;
+    }
+    fclose(f);
+    text[size] = 0;
+    if (!v4_text_assemble(t, text)) {
+        memcpy(was, t->message, sizeof was);
+        snprintf(t->message, sizeof t->message, "%.40s, %.170s", base, was);
+    }
+    free(text);
+    return !t->failed;
+}
+
 int v4_text_finish(v4_text *t)
 {
     if (t->failed) return 0;