fix: make memory lifecycles Luna-repairable

[dajiaohuang]

Problem

Fresh gpt-5.6-luna agents could create and revise memories but could not complete non-destructive retract/forget flows through the public MCP. Nested NPC, conversation, and playthrough-manifest failures also lacked enough field-level guidance for reliable recovery.

Solution

• expose retract/forget for campaign memory and actor knowledge without physical deletion
• preserve inactive history behind include_inactive with cursor binding
• restrict inactive actor-knowledge history to DM roles and validate nested booleans strictly
• enforce campaign revision guards atomically through SagaSmith Core feat: bound MCP collection pagination #23
• keep omitted-proposition retract/forget retries stable after later revisions
• require the compatible Core 0.2.1 contract and pin locked CI to its audited merge
• make manifest and NPC/conversation errors field-specific and recovery-oriented

Verification

• Core: 337 passed, 14 skipped; Python 3.11 and 3.12 CI passed
• Domain: 919 passed
• focused MCP lifecycle regression passed
• Ruff and Skills validators passed
• UI typecheck, Vitest, and build passed
• full MCP runs locally and in CI after PR creation

Fixes #66
Fixes #67
Fixes #68