[FEATURE] Strategy pack: Risk overlays (ratchet, ATR exit, progressive lock, cooldown)

[sjackson0109]

Implement composable risk overlay strategies: ratchet stop, ATR exit, progressive profit locking, and entry cooldown.

Dependency:

• Blocked by Strategy Catalogue schema: [FEATURE] Strategy Catalogue definition and schema #121
• Also aligns with existing feature requests [FEATURE] Ratchet stops #113 [FEATURE] ATR exits #114 [FEATURE] Progressive profit locking #115 [FEATURE] Entry cooldowns #116.

Implementation scope:

• Ratchet stop: stop floor only moves in favorable direction.
• ATR exit: volatility-adjusted stop/exit band.
• Progressive profit lock: staged lock levels as unrealized PnL increases.
• Entry cooldown: per-symbol/global cooldown after close/entry.
• Overlay architecture: attachable to main strategies without code duplication.

Acceptance criteria:

• Overlay entries registered in catalogue with class_type=risk_overlay.
• End-to-end tests show overlays can be composed together.
• UI/telemetry exposes active overlay states per position.