feat(arch): SECTION 25 opens - walls, openings, stairs and exterior chains as tools

engineering/arch/draw.py is the only module of the track that touches a
backend. It draws through draw_prims(role_layer=ARCH_ROLE_LAYER) and the
generic contract members, so it runs on both engines as written, and it writes
the plan onto the drawing: each element's ACADMCP_ARCH record on one of its own
entities (a wall's first face line, a door's leaf, a window's frame, a stair's
first riser) and, beside it under ACADMCP_ARCH_H, the handles that element
owns. read_plan reads the records back and never modifies the drawing.

arch_wall computes the whole network before and after the new walls and
redraws only the drawn walls whose outline changes - erasing exactly the
entities they own - and says which under redrawn. arch_opening hosts a door or
a window in a drawn wall found by id and redraws that wall cut; its tag
defaults to the next D1/W1 (K1/P1 in Turkish). A new wall that would leave a
drawn opening uncuttable, and an opening that runs into a junction, are refused
before anything is erased. arch_stair reports the Blondel value; it does not
enforce it.

exterior_chains gives each side up to three rows, nearest first: every jamb in
that facade, both faces of every wall meeting it, and the overall - from the
wall engine's own faces. A row that would only restate a farther one is not
emitted (ISO 129-1: each measurement once). The 10 mm / 8 mm row spacing is a
declared drafting default times the plot scale, not a standard value.

The arch tag is ranked after mech so the four tools file under a new
architecture group; alias records carry WALLADD/MLINE, DOORADD/WINDOWADD and
STAIRADD with English and Turkish shop words. Inventory regenerated; README
snapshot 233 tools (228 advertised) in 26 groups; registry snapshot
architecture: 4.

No new ActiveX member is called. Measured on AutoCAD 2026 in a scratch
document through ComBackend: shell + teed partition, D1 + W1, a straight 17-riser stair
and the bottom chains gave the same 20 wall LINEs (identical endpoints),
9 poche HATCHes, 1+1 door, 4 window lines, 11 dimensions and a read_plan
round trip as the headless engine.

Co-Authored-By: Claude Opus 5.5 (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:** 229 tools · 8 resources · 5 prompt templates · 4005 collected tests.
-> 229 is the **registered** count; a default install advertises 224 over `tools/list`,
+> **v1.5 release snapshot:** 233 tools · 8 resources · 5 prompt templates · 4005 collected tests.
+> 233 is the **registered** count; a default install advertises 228 over `tools/list`,
 > because `ENABLE_3D` is unset. `system_about` is the runtime authority.
 
 ## Why this exists
@@ -120,7 +120,7 @@ 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>229 tools in 25 groups; <code>TOOL_PACKS=core</code> hides the nine <code>pid_*</code> tools, the 22 environment tools and the 14 mechanical tools (<code>TOOL_PACKS=core,mech</code> keeps the last) from a client that needs none of them. 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>233 tools in 26 groups; <code>TOOL_PACKS=core</code> hides the nine <code>pid_*</code> tools, the 22 environment tools and the 14 mechanical tools (<code>TOOL_PACKS=core,mech</code> keeps the last) from a client that needs none of them. 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.