feat(elicitation): add subtraction and map-is-not-the-territory methods

[devilliersdutoit]

What

Add two elicitation methods to the advanced-elicitation registry: Subtraction (creative) and Map Is Not the Territory (framing).

Why

Both are well-established thinking tools missing from the set — Subtraction counters additive bias (improve by removing, not just adding); Map Is Not the Territory guards against trusting a lossy model before reality-checking it. They broaden the elicitation menu with no new control surface.
Fixes #2514

How

• Added Subtraction to the creative category and Map Is Not the Territory to framing in methods.csv
• Placed each in its category group and renumbered the trailing rows so the num index stays sequential
• No SKILL.md changes — methods are selected by name/number at runtime

Testing

npm run test:refs passes. npm run validate:refs surfaces only a pre-existing broken link in an unrelated bmad-document-project file; this change adds no new references.

[augmentcode]

🤖 Augment PR Summary

Summary: This PR expands the advanced-elicitation registry by adding two established thinking tools.

Changes:

• Added Subtraction as a new method under the creative category
• Added Map Is Not the Territory as a new method under the framing category
• Reordered/renumbered rows in methods.csv so the num index remains sequential within the registry

Technical Notes: No new runtime “control surface” was introduced; selection remains by name/number, and existing reference tests were reported as passing.

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[augmentcode]

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