refactor(components): remove md-commander widget

The journal now owns command history and tracking, so retire the md-commander widget. Its dice engine was extracted to src/components/dice in the previous commit.

Removes the custom element, tracker/command stores, completions, useCommander, Emmet parser, the doc entry, test fixtures, and the known-element catalog entry (reference docs regenerated).

BREAKING CHANGE: :md-commander is no longer a known element; content using it now fails tttk check with TTTK-D001.

content/commander-test.md

@@ -1,15 +0,0 @@
-# Commander Test
-
-:md-commander[./commands.csv]
-
-## Lonelog
-
-`我` 走进酒吧。
-
-`oracle` 酒吧里人多吗？
-
-`roll` d20 = 18 `prompt` 是的
-
-`fact` 酒吧里有很多人。
-
-:[blah]

content/commands.csv

@@ -1,6 +0,0 @@
-command,parameter,label,description,insertedText
-roll,emmet,2d6,2D6,2d6
-roll,emmet,d20,D20,d20
-track,emmet,monk,破戒佛爷,"破戒佛爷.bandit.monk[gd=4/4,str=14/14,cla=10,spi=8]"
-track,emmet,bandit,龙虎寨山贼,"龙虎寨山贼.bandit[gd=2/2,str=10/10,cla=10,spi=10]"
-track,emmet,khitan,契丹护卫,"契丹护卫.khitan.guard[gd=4/4,ap=2,str=14/14,cla=14,spi=14]"