fix v1.44.4: audit follow-up B2, B5, L4 sub-item

B2: the HTTP upload view failed OPEN when the config entry was
unavailable while the WS path failed closed — both now share one
may_write() policy helper (new auth.py) that denies non-admins when the
policy cannot be read.

B5: _finite now guards room rects, polygon vertices, view_box and
opening coordinates, not just layout positions; the declared
MAX_OPENINGS cap is finally enforced.

L4 (sub-item): every drag pipeline captures the pointer through the
tolerant helper (an inactive pointerId used to kill device/label/resize
drags); decor shapes gained a bounds clamp so they cannot be dragged far
outside the plan and persisted there.

+2 backend tests (16); both changelogs updated in this commit

docs/TESTING.md

@@ -50,6 +50,21 @@
       never silently linked); urls are rewritten only for confirmed copies
       [auto: unit logic.test + tests_backend]
 
+- [ ] Plans and PDFs load in a real browser (v1.44.3, B1 regression): open a
+      dashboard with an uploaded plan — the background renders and a manual link
+      opens; DevTools shows /api/houseplan/content/... returning 200 via a
+      signed url, while the same url without authSig returns 401
+      [auto: tests_backend + manual]
+- [ ] Auth policy is single-sourced (v1.44.4, B2): the HTTP upload and every WS
+      write use the same `may_write`, which denies non-admins when the config
+      entry is unavailable [auto: tests_backend]
+- [ ] Coordinates and caps (v1.44.4, B5): NaN/Infinity are refused on room
+      rects, polygon vertices, view_box and openings — not only in layout; the
+      openings list honours MAX_OPENINGS [auto: tests_backend]
+- [ ] Drag hardening (v1.44.4, L4 sub-item): every drag pipeline captures the
+      pointer through the tolerant helper; decor shapes cannot be dragged more
+      than a quarter of the plan outside the viewBox [auto: smoke_decor]
+
 ## Environments matrix
 
 Run the *core flows* (marked ★ below) in each environment at least once per minor release: