feat(task-9): SECTION 22 - std_part_list, std_part_insert, std_feature_draw

engineering/mech/stdparts.py turns the Task 8 tables into real blocks. catalogue()
searches 83 transcribed parts by designation, standard, size or family;
block_spec() emits the typed primitives and DESIG/STD/SIZE/MAT ATTDEFs
block_define takes, in side/top for fasteners and ISO 8826-1 simplified /
ISO 8826-2 detailed for bearings; insert_std_part() defines the block once,
inserts it and writes the std_part ACADMCP_MECH payload the skeleton pins, so
the parts list is a read of the drawing rather than a naming convention.
Threads follow ISO 6410 - minor at 0.8 x major, a thread-length limit line to
the major, a three-quarter minor arc in the end view.

std_feature_draw() adds a thread, a DIN 509 undercut, a DIN 471/472 groove, a
DIN 332 centre hole or an ISO 3601-2 O-ring groove to geometry that already
exists. Its dimensions come from the shared standards registry, never from this
module: an absent table, a size outside coverage or a row missing a dimension is
refused by name, and the DIN 509 relief is drawn from the profile its table
publishes rather than reconstructed here. DIN 332 form R is refused outright.
An unknown designation is refused with the nearest catalogue entries; nothing is
drawn approximately.

SECTION 22 registers the three tools in the new mech pack, with alias records
(INSERT plus shop-floor synonyms in English and Turkish), a regenerated tool
inventory, the README release snapshot at 207 tools in 24 groups, and the frozen
group-size snapshot gaining mech: 3.

Two plan corrections, both verified by running the code:

* the plan's @cad_tool summaries for std_part_insert (118 chars) and
  std_feature_draw (130) overran discovery.serialize.MAX_SUMMARY_CHARS = 110, so
  tests/test_tool_registry.py::test_no_authored_summary_is_long_enough_to_be_truncated
  failed - they would have shipped rendered as "...". Both are shortened to 99
  and 104 characters with the same content.
* the plan's file list omitted tests/test_tool_packs.py, which pins the pack
  registry, the tool_packs report and the group count. It now carries MECH_TOOLS
  and distinguishes ALL_PACKS (declaration order, what "available" reports) from
  ALL_PACKS_ENABLED (sorted, what "enabled" reports) - those two lists stopped
  being the same list when "mech" was appended after "settings".

No new ActiveX member is called: the module drives block_list / block_define /
block_insert / entity_set_xdata / entity_create_* only. The COM path was still
executed live once on AutoCAD 2026 in a scratch document created and closed by
the probe: the bolt block defined with layers CENTER+GEOMETRY, attributes read
back as DESIG/STD/SIZE/MAT = ISO 4014 - M12x60 / ISO 4014 / M12x60 / 8.8, the
ACADMCP_MECH std_part payload round-tripped through entity_get_xdata,
STD_ISO_15_6205_SIMPLIFIED inserted, and the M20 thread's three primitives
landing on GEOMETRY.

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

README.md

@@ -27,8 +27,8 @@ Live through COM on Windows, or headless through ezdxf anywhere — one typed co
 
 </div>
 
-> **v1.5 release snapshot:** 204 tools · 8 resources · 5 prompt templates · 3284 collected tests.
-> 204 is the **registered** count; a default install advertises 199 over `tools/list`,
+> **v1.5 release snapshot:** 207 tools · 8 resources · 5 prompt templates · 3284 collected tests.
+> 207 is the **registered** count; a default install advertises 202 over `tools/list`,
 > because `ENABLE_3D` is unset. `system_about` is the runtime authority.
 
 ## Why this exists
@@ -117,7 +117,7 @@ Claude Desktop, Cursor, or any stdio MCP host. For HTTP: `autocad-mcp --transpor
 | Quality loop | `drawing_preflight` → `drawing_plan` → `drawing_critique` → `drawing_refine` → `drawing_finalize` (0–100 score) |
 | Delivery | `drawing_deliver`: DXF/PDF/PNG + SHA-256 manifest + reopen-parity checks |
 
-<sub>204 tools in 23 groups; <code>TOOL_PACKS=core</code> hides the nine <code>pid_*</code> tools and the 22 environment tools (<code>TOOL_PACKS=core,settings</code> keeps the latter) from a client that needs neither. Plus 8 resources that cost nothing in the tool budget (<code>autocad://drawing/info</code>, <code>layers</code>, <code>blocks</code>, <code>entities/stats</code>, <code>entities/{layer_name}</code>, <code>system/status</code>, <code>pid/symbols</code>, <code>standards/isa51</code>) and 5 prompt templates.</sub>
+<sub>207 tools in 24 groups; <code>TOOL_PACKS=core</code> hides the nine <code>pid_*</code> tools and the 22 environment tools (<code>TOOL_PACKS=core,settings</code> keeps the latter) from a client that needs neither. Plus 8 resources that cost nothing in the tool budget (<code>autocad://drawing/info</code>, <code>layers</code>, <code>blocks</code>, <code>entities/stats</code>, <code>entities/{layer_name}</code>, <code>system/status</code>, <code>pid/symbols</code>, <code>standards/isa51</code>) and 5 prompt templates.</sub>
 
 **Two rules worth knowing.** Every coordinate in and out of a tool is WCS on both engines — the one exception is TEXT `rotation`, which stays in the entity frame because a mirrored TEXT is mirror-imaged and no scalar angle expresses that. And never read vertices back and shoelace them: that loses **28.2%** of the area on a semicircular edge, silently. `analysis_measure_entity(handle)` reads the real geometry and states its own accuracy.