feat(attribute): route ATTMAN/BATTMAN to the attribute editor (ATTEDIT)

ATTMAN and BATTMAN previously produced a command-line listing of block
attributes. Route both to the attribute editor instead: extract the bare
ATTEDIT behavior into a shared open_attedit_dialog helper (edit the
selected block, or start the block-pick command) and call it from the
ATTEDIT, ATTMAN, and BATTMAN arms.

Kept as a match arm rather than an ocad.pgp alias so it works for
existing users, whose config pgp is only seeded on first run.

Replace the listing regression tests with one asserting ATTMAN and
BATTMAN behave byte-for-byte like ATTEDIT.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

COMMANDS.md

@@ -194,7 +194,7 @@ Status of every standard CAD command in Open CAD Studio:
 | `ATTEXT` | — | Extract attributes (legacy) | ✅ |
 | `ATTSYNC` | — | Synchronize attribute definitions | ✅ |
 | `BLOCKPALETTE` | — | Multi-view block palette (command-line list) | 🔶 |
-| `ATTMAN` | `BATTMAN` | Attribute manager (command-line list) | 🔶 |
+| `ATTMAN` | `BATTMAN` | Block attribute manager (opens the attribute editor) | ✅ |
 | `XBIND` | XB | Bind xref elements to drawing | ❌ |
 | `XOPEN` | — | Open xref for editing | ✅ |
 | `BSAVE` | — | Save block in editor | ❌ |