fix(physics): P5 commit 3 - retire TS-35, close #167 (ConstraintManager leash)

PhysicsBody.IsFullyConstrained now reflects real ConstraintManager state
(pushed every tick by the same per-tick pumps commit 2 wired), so
jump_is_allowed's already-ported gate (WeenieError 0x47) actually fires
while an object is rubber-banding hard against a server position
correction, closing the last piece of #167.

Housekeeping:
- Delete register row TS-35 (retired: the write side is no longer stubbed).
- Rewrite the stale doc comments on PhysicsBody.IsFullyConstrained,
  ConstraintManager (class + IsFullyConstrained), PositionManager.ConstrainTo,
  EntityPhysicsHost.PositionManager, and PlayerMovementController.PositionManager
  that described the leash as permanently unarmed/stubbed.
- Close #167 in ISSUES.md citing the research doc and commits e0629145 /
  7719d25b.
- Add an "as-ported" addendum to
  docs/research/2026-07-30-constraint-leash-constants.md naming the actual
  current seam owners (the doc's own open question flagged this as
  implementer-verify-required post-J-slices).
- Update docs/plans/2026-07-29-physics-parity-campaign.md's P5 status and
  CLAUDE.md's Campaign P summary to reflect #167's closure (items #153/#72
  remain open in P5).

Verification: complete solution suite green - 9,978 tests, 5 skips, 0
failures across all 9 test projects (Core.Tests, Runtime.Tests, App.Tests,
Headless.Tests, Core.Net.Tests, Content.Tests, UI.Abstractions.Tests,
Bake.Tests, Cli.Tests).

docs/plans/2026-07-29-physics-parity-campaign.md

@@ -220,6 +220,19 @@ RestrictionTables residuals. Suite 9,956/0/5.
 
 ### P5 — Deferred fidelity — closes #167, #153, #72
 
+**Status (2026-07-30): item 1 (#167) COMPLETE.** Both blockers resolved
+without Ghidra/cdb — the two x87-elided constants were byte-decoded
+straight from the matching binary's raw machine code
+(`docs/research/2026-07-30-constraint-leash-constants.md`). The leash is
+now armed at every current acdream inbound-position acceptance seam
+(`ConstraintDistance`, `LiveEntityNetworkUpdateController`,
+`PlayerMovementController.SetPosition`/`BlipPosition`), the per-tick
+`PhysicsBody.IsFullyConstrained` push replaces the always-false stub, and
+register row TS-35 is deleted. Full Core/Runtime/App suites pass with new
+conformance tests (leash-armed jump refusal, teleport-vs-blip
+anchor/teardown, taper reduction, remote-tick push). Items 2 (#153) and 3
+(#72) remain open.
+
 1. **#167:** decode the two unknown x87 ConstraintManager constants
    (Ghidra) and port leash arming.
 2. **#153:** the far-teleport arrival onto an unstreamed landblock near