fix: align TrustLevel enum with RFC-002 v1.4

[beonde]

Summary

Corrects trust level naming in TrustLevel enum and documentation to match RFC-002 v1.4 §5.

Problem

The Python SDK's TrustLevel enum had incorrect level names that didn't match the authoritative RFC-002 specification:

Level	Before (Wrong)	After (Correct per RFC-002)
0	Self-Signed	Self-Signed (SS) ✅
1	DV	REG (Registered)
2	OV	DV (Domain Validated)
3	EV	OV (Organization Validated)
4	CV	EV (Extended Validated)

CV (Continuous Validation) doesn't exist in RFC-002. The code invented a level that the spec doesn't define.

Impact

• ⚠️ BREAKING CHANGE for documentation consumers - Anyone who read our docs and built policies around "Level 1 = DV" will need to update their mental model
• ✅ No code changes required - Integer values (0-4) are unchanged. The actual verification logic was already correct.
• ✅ All 269 tests pass

Files Changed

File	Change
capiscio_mcp/types.py	Fixed TrustLevel enum docstring and inline comments
README.md	Updated trust level table
docs/index.md	Updated trust level table
docs/getting-started/quickstart.md	Updated trust level table
docs/guides/server-side.md	Fixed code comment (CV → EV)

RFC-002 v1.4 §5 Reference

| Level | Name                     | Validation                              |
|-------|--------------------------|----------------------------------------|
| "0"   | Self-Signed (SS)        | None. Agent uses did:key                |
| "1"   | Registered (REG)        | Account registration                    |
| "2"   | Domain Validated (DV)   | DNS TXT / HTTP challenge                |
| "3"   | Organization Validated (OV) | DUNS, legal entity lookup           |
| "4"   | Extended Validated (EV) | Manual review + legal agreement         |

Testing

pytest tests/ -v
# 269 passed ✅

Checklist

• Trust level enum matches RFC-002 v1.4
• All documentation tables updated
• All tests pass
• Commit message explains breaking change