Move BASIC fixtures into the editable language corpus

Move every program and expectation out of tests/reference and register the unified tests/language corpus as local cases. Remove the old immutable-corpus protections from build, maintenance, and documentation paths.

Co-authored-by: andrew <andrew@aklabs.net>

tests/reference/examples/bubblesort.bas

@@ -1,29 +0,0 @@
-10 DIM A#(5)
-15 ITERATIONS# = 0 
-20 A#(0) = 5
-21 A#(1) = 2
-22 A#(2) = 4
-23 A#(3) = 1
-24 A#(4) = 3
-25 PRINT "BEFORE SORTING: "
-26 FOR I# = 0 TO 4
-27     PRINT A#(I#)
-28 NEXT I#
-30 CHANGED# = 0
-32 ITERATIONS# = ITERATIONS# + 1
-35 FOR I# = 0 TO 3
-45     J# = I#+1
-46     REM PRINT "COMPARING INDEXES " + I# + " (" + A#(I#) + ") AND " + J# + "
-50     IF A#(I#) <= A#(J#) THEN GOTO 100
-55     REM PRINT "SWAPPING INDEXES " + I# + " AND " + J#
-60     TMP# = A#(I#)
-70     A#(I#) = A#(J#)
-80     A#(J#) = TMP#
-85     CHANGED# = CHANGED# + 1
-100 NEXT I#
-110 IF CHANGED# <> 0 THEN GOTO 30
-115 PRINT "AFTER SORTING:"
-120 FOR I# = 0 TO 4
-130   PRINT A#(I#)
-140 NEXT I#
-145 PRINT "SORTED IN " + ITERATIONS# + " ITERATIONS"

tests/reference/examples/bubblesort.txt

@@ -1,13 +0,0 @@
-BEFORE SORTING: 
-5
-2
-4
-1
-3
-AFTER SORTING:
-1
-2
-3
-4
-5
-SORTED IN 4 ITERATIONS

tests/reference/examples/factorial.bas

@@ -1,10 +0,0 @@
-10 N# = 5
-20 RESULT# = 1
-30 GOSUB 100
-40 PRINT "FACTORIAL(5) IS " + RESULT#
-50 QUIT
-100 IF N# <= 1 THEN RETURN
-110 RESULT# = RESULT# * N#
-120 N# = N# - 1
-130 GOSUB 100
-140 RETURN

tests/reference/examples/factorial.txt

@@ -1 +0,0 @@
-FACTORIAL(5) IS 120

tests/reference/examples/strreverse.bas

@@ -1,7 +0,0 @@
-10 SOURCE$ = "HELLO"
-20 STRLEN# = LEN(SOURCE$) - 1
-30 REV$ = ""
-40 FOR I# = STRLEN# TO 0 STEP -1
-50   REV$ = REV$ + MID(SOURCE$, I#, 1)
-60 NEXT I#
-70 PRINT "REVERSED: " + REV$

tests/reference/examples/strreverse.txt

@@ -1 +0,0 @@
-REVERSED: OLLEH