Validator: simplify severity model from 4 tiers to 2 (blocking + advisory)

[arjunmehta-git]

Context

The validator currently has 5 reporting functions (`warn`, `advisory`, `reportStyleIssue`, `reportDesignAdvisory`, `reportContractAdvisory`) controlled by 5 CLI flags (`--warn`, `--no-baseline`, `--style-debt`, `--contract-debt`, `--strict-consistency`). This creates a complex combinatorial matrix:

	Default	--warn	--strict	--style-debt	--contract-debt
Style	skip	skip	error	warning	skip
Design	warn	warn	error	warning	warning
Contract	skip	skip	error	skip	warning
Blocking	error	error	error	error	error

Problem

• 5 flags and 4 severity tiers are hard to reason about
• The style/contract distinction existed primarily because of v1beta1 legacy debt and v1beta2-draft, both of which are now resolved or removed
• Contributors and CI configurations struggle to pick the right combination

Proposal

Collapse to 2 tiers: blocking and advisory.

• All advisory rules (style, design, contract) emit warnings by default
• `--strict` promotes all to errors
• `--baseline` suppresses known issues
• Drop `--style-debt` and `--contract-debt` as separate flags
• Reduce to 3 flags: `--strict`, `--baseline`, `--warn`
• Eliminate `consistency-policy.js` entirely — replace with a single inline check
• Simplify the 6 Makefile targets to 3: `validate-schemas`, `validate-schemas-strict`, `audit-schemas`

Impact

• Validator code: delete `build/lib/consistency-policy.js`, simplify `validate-schemas.js` reporting
• Makefile: reduce 6 targets to 3
• CI: update `.github/workflows/schema-audit.yml`
• Tests: simplify `tests/validate-schemas-consistency-policy.test.js`

References

Identified in schema validator audit — Section 3d (The 3-Tier Severity System).

[Junnygram]

can you assign me @miacycle