feat(templates): five bundled templates built by the server's own tools; drawing_new(template=name)

SECTION 19 grows to five tools with drawing_template_list; drawing_new takes a
bundled name (iso_a3_mech, iso_a1_arch, iso_a3_pid, ansi_b_mech, ansi_d_arch)
or a .dwt/.dxf path and reports template: {name|path, path, source}.

scripts/build_templates.py builds templates/*.dxf through EzdxfBackend
(layer set, header DIM variables until group S's styles land, drawing_settings,
sheet tab, ISO 5457 frame on A3, page_setup_apply) and --check pins them
reproducible. One drift the plan's same-process measurement could not see is
fixed at the source rather than masked: ezdxf orders CLASSES by set iteration,
so two processes disagreed on LAYOUT / ACDBPLACEHOLDER; the section is re-keyed
(required list first, then by name) before the save.

The root .gitignore ignores *.dxf as generated output; templates/*.dxf is
un-ignored there, since the bundled set is the one DXF that is committed.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FKFStjEFzpGyLq5bMpWxTd

discovery/aliases.py

@@ -445,7 +445,13 @@ TOOL_ALIASES: dict[str, ToolAliases] = {
     ),
     "drawing_new": ToolAliases(
         acad=("NEW", "QNEW"),
-        synonyms=("new drawing", "start a drawing", "blank sheet", "create a file"),
+        synonyms=(
+            "new drawing",
+            "start a drawing",
+            "blank sheet",
+            "create a file",
+            "start from a bundled template",
+        ),
     ),
     "drawing_open": ToolAliases(
         acad=("OPEN",),
@@ -1445,6 +1451,17 @@ TOOL_ALIASES: dict[str, ToolAliases] = {
             "plot the whole drawing set",
         ),
     ),
+    "drawing_template_list": ToolAliases(
+        acad=(),
+        synonyms=(
+            "which templates are there",
+            "bundled templates",
+            "iso a3 template",
+            "ansi b sheet",
+            "start from a standard sheet",
+            "dwt list",
+        ),
+    ),
     "page_setup_apply": ToolAliases(
         acad=("PAGESETUP",),
         synonyms=(