refactor: formulas use JSON instead of YAML (gt-8tmz)

JSON for consistency with beads (issues.jsonl, molecules.jsonl).
Agents create/manage formulas; humans use visualizers.

- Simpler parsing (Go built-in JSON)
- No YAML gotchas
- Agents generate JSON flawlessly

.beads/formulas/security-audit.formula.yaml

@@ -1,48 +0,0 @@
-# security-audit.formula.yaml
-# AOP aspect for security scanning at implementation boundaries
-
-formula: security-audit
-type: aspect
-description: |
-  Cross-cutting security concern. Applies security scanning
-  before and after implementation steps.
-
-  This is an ASPECT - it doesn't run standalone. Apply it
-  to other formulas using --with-aspect.
-version: 1
-
-pointcuts:
-  - glob: "*.implement"
-  - glob: "*.submit"
-
-advice:
-  around:
-    before:
-      - id: security-prescan
-        description: |
-          Pre-implementation security check.
-
-          - Review for secrets/credentials in scope
-          - Check dependencies for known vulnerabilities
-          - Verify security requirements are understood
-        args:
-          target: "{step.id}"
-
-    after:
-      - id: security-postscan
-        description: |
-          Post-implementation security scan.
-
-          - Scan new code for vulnerabilities (SAST)
-          - Check for hardcoded secrets
-          - Verify auth/authz patterns
-          - Review for OWASP Top 10 issues
-        args:
-          target: "{step.id}"
-        output:
-          approved: boolean
-          findings: list
-
-      - gate:
-          condition: "security-postscan.output.approved == true"
-          message: "Security approval required before proceeding"