feat(principles): add "weakest-link-wisdom" principle for constraint identification

## Summary
Add a new principle focused on identifying and learning from the weakest link/constraint in any system, inspired by biblical wisdom.

## Proposed Principle: Weakest Link Wisdom

**Core Concept**: The strength of a system is determined by its weakest link. Wisdom comes from identifying, understanding, and strengthening that link.

## Biblical Foundation

### Primary Scripture - 1 Corinthians 12:22-23
> "On the contrary, those parts of the body that seem to be weaker are indispensable, and the parts that we think are less honorable we treat with special honor."

### Supporting Scriptures
- **Matthew 25:40**: "Whatever you did for one of the least of these brothers and sisters of mine, you did for me."
- **Luke 15:4**: The shepherd leaves 99 sheep to find the one that's lost (the constraint/weakness)
- **2 Corinthians 12:9**: "My power is made perfect in weakness"

## Principle Definition

```markdown
# Weakest Link Wisdom

The principle that system performance is limited by its weakest component, and true wisdom comes from:
1. Identifying the constraint with humility
2. Understanding why it exists
3. Honoring it with focused attention
4. Learning from what it reveals about the whole system

## In Practice
- Look for the bottleneck, not the busy work
- The constraint teaches us more than our strengths
- What seems "weakest" may be most essential
- Strengthen the weak link before optimizing elsewhere

## Connection to Other Principles
- Complements Five Focusing Steps (procedural implementation)
- Supports Systems Stewardship (caring for all parts)
- Enables Selective Optimization (know where to focus)
```

## Why This Matters
- Easy to remember: "weakest link wisdom"
- Biblically grounded in honoring what seems weak
- Practical for debugging, optimization, and system design
- Encourages humility and learning from constraints

## Implementation
- Add to `knowledge/principles/weakest-link-wisdom.md`
- Reference in procedures like Five Focusing Steps
- Use in retros when identifying bottlenecks

Principle: systems-stewardship

Start with knowledge/principles/weakest-link-wisdom.md and compare its requested structure with the project’s existing principle files. Add the proposed principle content, then check how the Five Focusing Steps and other referenced principles are organized before adding the requested connections. Done means the new principle exists at the specified path and its stated references are included.

Written by the indexing model from the issue text.