Add Type and More, and the file stream they are built on

Two applications that read a file too big for Data Memory: Type prints one,
More pages it. Both sit on fileStream.asm, which wraps osFileInfo and
osFileBlock into open-and-next so an application walks a file's blocks without
repeating the service calls.

The disk fixture is deliberately awkward: readable.txt crosses several blocks
and carries no zero byte to be mistaken for an end marker, and empty.txt says
that zero blocks is a valid file rather than an error.

These three files were written by ChatGPT, as their headers record.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW

Programs/CosmOS/Source/fileStream.asm

@@ -0,0 +1,141 @@
+; Read a named file from beginning to end, one block at a time.
+;
+;   DP0 = filename
+;   CALL fileStreamOpen       Q = 0, or the osFileInfo error
+;   CALL fileStreamNext       Q = 0, or the osFileBlock error
+;                             DP3 = bytes in FileStreamBlock; zero means EOF
+;
+; This is application-side machinery built on CosmOS services, not a filesystem and not
+; yet an OS stream. Open remembers the address of the caller's filename, which must remain
+; valid until the one stream is finished.
+;
+; Written by ChatGPT for Anachronaut's SplitBit
+
+#Program
+fileStreamOpen:
+  SETD.3 FileStreamName
+  STD.0.3
+  SWI osFileInfo
+  BNQ fileStreamReturn
+  PSHD.3
+  POPB
+  POPA
+  SETD.3 FileStreamBlocks
+  STA.3
+  INCD.3
+  STB.3
+  SETD.3 FileStreamIndex
+  RSTA
+  STA.3
+  INCD.3
+  STA.3
+fileStreamReturn:
+  RET
+
+fileStreamNext:
+  SETD.3 FileStreamBlocks
+  LDA.3
+  INCD.3
+  LDB.3
+  OR
+  BRQ fileStreamEnd
+  SETD.3 FileStreamName
+  LDD.0.3
+  SETD.1 FileStreamBlock
+  SETD.3 FileStreamIndex
+  LDA.3
+  INCD.3
+  LDB.3
+  SWI osFileBlock
+  BNQ fileStreamReturn
+
+  ; DP3 is the service's return value and also the pointer this routine uses for all of
+  ; its bookkeeping. Keep the value before touching the pointer, then restore it at the
+  ; one successful return below.
+  PSHD.3
+  POPB
+  POPA
+  SETD.3 FileStreamCount
+  STA.3
+  INCD.3
+  STB.3
+
+  ; Index++.
+  SETD.3 FileStreamIndex
+  INCD.3
+  LDA.3
+  INCA
+  STA.3
+  BNC fileStreamTakeBlock
+  DECD.3
+  LDA.3
+  INCA
+  STA.3
+fileStreamTakeBlock:
+  ; Blocks--.
+  SETD.3 FileStreamBlocks
+  INCD.3
+  LDA.3
+  BRA fileStreamBlocksBorrow
+  DECA
+  STA.3
+  BRI fileStreamReadReturn
+fileStreamBlocksBorrow:
+  INIA 0xFF
+  STA.3
+  DECD.3
+  LDA.3
+  DECA
+  STA.3
+fileStreamReadReturn:
+  SETD.3 FileStreamCount
+  LDD.3.3
+  RET
+fileStreamEnd:
+  ; There is no reset-pointer instruction. Two zero bytes through the Stack are the
+  ; literal construction of a zero Data Pointer.
+  RSTA
+  PSHA
+  PSHA
+  POPD.3
+  RET
+
+; DP2 names a big-endian sixteen-bit byte count. Decrement it, returning Q = 0 when it
+; reached zero and nonzero while bytes remain. This is shared because correctly counting
+; a full 0x0100-byte block is the least interesting part of both applications to duplicate.
+fileStreamTakeRemaining:
+  INCD.2
+  LDA.2
+  BRA fileStreamRemainingBorrow
+  DECA
+  STA.2
+  DECD.2
+  LDB.2
+  INCD.2
+  LDA.2
+  OR
+  RET
+fileStreamRemainingBorrow:
+  INIA 0xFF
+  STA.2
+  DECD.2
+  LDA.2
+  DECA
+  STA.2
+  LDB.2
+  INCD.2
+  LDA.2
+  OR
+  RET
+
+#Data
+FileStreamName:
+  0x00 0x00
+FileStreamBlocks:
+  0x00 0x00
+FileStreamIndex:
+  0x00 0x00
+FileStreamCount:
+  0x00 0x00
+FileStreamBlock:
+  #Reserve 0d256