Improve clarity of intent preset feature comparison table in README

[27Bslash6]

Problem

The current feature comparison table for intent presets (@cache.minimal, @cache.production, @cache.secure) in the README is incomplete and could be clearer:

Missing presets

The table only covers minimal, production, and secure. The dev and test presets are mentioned in a collapsed <details> block below with code examples but no feature comparison — a reader has to read the source to understand what they enable/disable.

Missing features

Several features that presets actually configure are absent from the table:

Feature actually configured	In table?
Circuit Breaker	✅
Adaptive Timeouts	✅
Monitoring (Prometheus/tracing/logging)	✅ (as "Monitoring")
Integrity Checking	✅
Encryption	✅
L1 SWR (stale-while-revalidate)	❌
L1 Invalidation	❌
L1 Namespace Index	❌
Backpressure	❌
Structured Logging	❌ (collapsed into "Monitoring")
Tracing	❌ (collapsed into "Monitoring")

Ambiguous descriptions

• "✅ Full" for Monitoring is vague — does it mean Prometheus + tracing + structured logging? The dev preset enables tracing + structured logging but disables Prometheus, which would be a useful distinction.
• "✅ Enabled" vs "✅ Enforced" for Integrity Checking — the distinction matters (secure forces it non-overridable) but this nuance is easy to miss.

Suggested improvement

A single comprehensive table covering all 5 presets with the full feature set:

Feature	minimal	dev	test	production	secure
Circuit Breaker	-	✅	-	✅	✅
Adaptive Timeouts	-	✅	-	✅	✅
Backpressure	✅	✅	-	✅	✅
Integrity Checking	-	✅	-	✅	✅ 🔒
Encryption	-	-	-	-	✅ Required
L1 SWR	-	✅	-	✅	✅
L1 Invalidation	-	-	-	✅	✅
L1 Namespace Index	-	-	-	✅	✅
Prometheus Metrics	-	-	-	✅	✅
Tracing	-	✅	-	✅	✅
Structured Logging	-	✅	-	✅	✅
Use Case	High throughput	Debugging	Unit tests	Production	Compliance

🔒 = non-overridable (security invariant)

This makes the progressive complexity visible at a glance and helps users pick the right preset without reading source code.

Source of truth

All values derived from DecoratorConfig.minimal(), .dev(), .test(), .production(), .secure() class methods in src/cachekit/config/decorator.py.