v1.1.0 — per-conversation switch

The switch becomes per conversation.

• Each conversation has its own position, keyed by session id; a new conversation starts off.
• Subagents inherit the position of the conversation that created them.
• GET /rea-toggle/state takes ?session=; POST requires session in the body.
• Positions persist per conversation, capped at the 500 most recently changed; a v1 file is ignored rather than misread.
• New defaultEnabled: true restores the pre-plugin behaviour.

Fixed: one tools/change could wedge the whole Harness. Lifting stale restrictions happened outside the reconcile latch, so those disposals re-entered the event listener with the latch still open. Measured: one external event produced ~41,000 register/dispose pairs and the UI stopped accepting messages. All lifting now happens inside the latch, and a counting regression test pins the bound.

Asset dsh-rea-toggle.tgz is the prebuilt package, deliberately version-free so releases/latest/download/ keeps resolving.