[2.23.0] Major update to agent-native-architecture skill (#70)

Align skill with canonical Agent-Native Architecture document:

## Core Changes
- Restructure SKILL.md with 5 named principles from canonical:
  - Parity: Agent can do whatever user can do
  - Granularity: Prefer atomic primitives
  - Composability: Features are prompts
  - Emergent Capability: Handle unanticipated requests
  - Improvement Over Time: Context accumulation

- Add "The test" for each principle
- Add "Why Now" section (Claude Code origin story)
- Update terminology from "prompt-native" to "agent-native"
- Add "The Ultimate Test" to success criteria

## New Reference Files
- files-universal-interface.md: Why files, organization patterns, context.md pattern, conflict model
- from-primitives-to-domain-tools.md: When to add domain tools, graduating to code
- agent-execution-patterns.md: Completion signals, partial completion, context limits
- product-implications.md: Progressive disclosure, latent demand discovery, approval matrix

## Updated Reference Files
- mobile-patterns.md: Add iOS storage architecture (iCloud-first), "needs validation" callouts, on-device vs cloud section
- architecture-patterns.md: Update overview to reference 5 principles and cross-link new files

## Anti-Patterns
- Add missing anti-patterns: agent as router, build-then-add-agent, request/response thinking, defensive tool design, happy path in code

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude <noreply@anthropic.com>

plugins/compound-engineering/skills/agent-native-architecture/references/architecture-patterns.md

@@ -1,5 +1,12 @@
 <overview>
-Architectural patterns for building prompt-native agent systems. These patterns emerge from the philosophy that features should be defined in prompts, not code, and that tools should be primitives.
+Architectural patterns for building agent-native systems. These patterns emerge from the five core principles: Parity, Granularity, Composability, Emergent Capability, and Improvement Over Time.
+
+Features are outcomes achieved by agents operating in a loop, not functions you write. Tools are atomic primitives. The agent applies judgment; the prompt defines the outcome.
+
+See also:
+- [files-universal-interface.md](./files-universal-interface.md) for file organization and context.md patterns
+- [agent-execution-patterns.md](./agent-execution-patterns.md) for completion signals and partial completion
+- [product-implications.md](./product-implications.md) for progressive disclosure and approval patterns
 </overview>
 
 <pattern name="event-driven-agent">