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/app/commands/blocks.rs

@@ -53,7 +53,7 @@ impl OpenCADStudio {
                 }
             }
 
-            "COPYCLIP" | "CC" => {
+            "COPYCLIP" => {
                 let handles: Vec<_> = self.tabs[i]
                     .scene
                     .selected_entities()
@@ -142,7 +142,7 @@ impl OpenCADStudio {
                 }
             }
 
-            "CUTCLIP" | "CX" => {
+            "CUTCLIP" => {
                 let handles: Vec<_> = self.tabs[i]
                     .scene
                     .selected_entities()
@@ -179,7 +179,7 @@ impl OpenCADStudio {
                 }
             }
 
-            "PASTECLIP" | "PC" => {
+            "PASTECLIP" => {
                 if self.clipboard.is_empty() {
                     self.command_line.push_error("Clipboard is empty.");
                 } else {
@@ -386,7 +386,7 @@ impl OpenCADStudio {
             // ADCENTER / CONTENTBROWSER — report the drawing's named content
             // (blocks and layers) from the command line in place of the browser
             // panel.
-            "ADCENTER" | "CONTENTBROWSER" | "ADC" => {
+            "ADCENTER" | "CONTENTBROWSER" => {
                 let blocks = self.tabs[i].scene.custom_block_names();
                 let layers: Vec<String> = self.tabs[i]
                     .scene
@@ -476,7 +476,7 @@ impl OpenCADStudio {
                 }
             }
 
-            "XATTACH" | "XA" => {
+            "XATTACH" => {
                 // Launch the file picker; XAttachPickResult will start the command.
                 return Some(Task::done(Message::XAttachPick));
             }
@@ -498,7 +498,7 @@ impl OpenCADStudio {
                 }
             }
 
-            "XREF" | "XR" => {
+            "XREF" => {
                 // List all xref blocks in the current drawing.
                 let xrefs: Vec<String> = self.tabs[i]
                     .scene