feat(alias): centralize command aliases in user-editable ocad.pgp (#286/#288)

Command aliases (L→LINE, CC→COPYCLIP) were scattered across dispatch match
arms and CommandRegistration name arrays. Move them all into a single
user-editable file:

- assets/ocad.pgp: shipped default alias table (ALIAS,*COMMAND format),
  embedded and copied to config/ocad.pgp on first launch; only that user
  copy is read after. AA→AREA default closes #286.
- resolve_alias() rewrites the leading command token at the top of
  dispatch_command_inner, so aliases resolve for every path (families,
  plugins, Repeat menu). Args after the first space are untouched.
- Autocomplete hides alias keys and, when the whole input is an alias,
  surfaces its target command as the top (highlighted) suggestion so the
  highlight matches what Enter runs (AA→AREA, L→LINE).
- ALIASEDIT opens a new editor modal (add/edit/delete rows) with an Apply
  button; Apply persists to ocad.pgp, closing discards unapplied edits.
- Strip alias tokens from all 8 dispatch match-arm files and 71 module
  CommandRegistration arrays, keeping canonical/synonym/distinct-command
  names. ocad.pgp is now the sole source: deleting or remapping an alias
  there takes effect. CUI stays on the keyboard-shortcut panel.

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

src/modules/draw/modify/offset.rs

@@ -816,7 +816,7 @@ impl CadCommand for OffsetCommand {
 
 
 // ── Autocomplete registry ─────────────────────────────────
-inventory::submit!(crate::command::CommandRegistration { names: &["O", "OFFSET"] });  // OffsetCommand
+inventory::submit!(crate::command::CommandRegistration { names: &["OFFSET"] });  // OffsetCommand
 
 #[cfg(test)]
 mod offset_tests {