fix(context): sync to the estate canonical context-sync.sh (ADR-0019)

Caught by the new estate-wide context-sync-drift gate (infra, ADR-0019).
This repo's copy had diverged from the canonical established in dma-cli/
infra -- synced to it, dead Cursor/Aider artifacts removed (2026-09-01
harness decision), Taskfile's drift assertion narrowed to match, adapters
regenerated against the current canonical AGENT.md.

Changed:
D  .aider.conf.yml
D  .aider.conventions.md
M  .context/system-prompt.txt
D  .cursorrules
M  AGENTS.md
M  CLAUDE.md
M  Taskfile.yml
M  scripts/context-sync.sh

Refs: ADR-0019 (infra)

Taskfile.yml

@@ -33,5 +33,3 @@ tasks:
     cmds: [bash scripts/context-sync.sh claude]
   context:sync:agents:
     cmds: [bash scripts/context-sync.sh agents]
-  context:sync:cursor:
-    cmds: [bash scripts/context-sync.sh cursor]