Stop agent factory loops: finish the list, one PR, no recursive hunts

[jmjava]

The 2ccd cloud agent ran ~22 hours and opened PRs #73–#149 by hunting the next YAML key / fail-closed hole after each micro-PR, spawning recursive “hunt remaining bugs” children, and stopping to ask for merges mid-list.

This adds a hard session contract so the next agent:

• Finishes the user’s task list in one run on one branch / one PR
• Does not ask the user to merge, rebase, or continue
• Batches isomorphic leftover keys instead of one-key-per-PR
• Stops when the assigned work is done (empty milestones/README.md Active means stop, not “pick the next config key”)
• Hard-stops if the next patch is the same shape as the last

Changes

• .cursor/rules/no-factory-loop.mdc (alwaysApply)
• Session contract at the top of AGENTS.md plus a Cloud-instructions pointer
• milestones/README.md: hunting program closed; Active is human-assigned only; Fail closed when scene-spec layout gaps coerce bools to 1.0 #148 moved to Shipped

What this cannot do by itself

Repo rules cannot override Cursor Cloud’s platform prompt. If an agent still opens a second isomorphic PR or starts a hunt you did not ask for, kill that run. Prompt new work with: “Do the whole list on one PR. Do not ask me to merge. Stop when the list is done.”