Add Arm CCA attestation support (v1.x)

[AI-God-Dev]

Problem

Arm CCA is needed for edge/mobile adoption and broader TEE coverage.

Scope

• Define CCA evidence fields (measurement + report data binding).
• Add parser + verifier stubs.
• Extend verifier to accept platform: arm-cca.

Acceptance Criteria

• Evidence schema documented.
• Parser stub compiles with permissive-mode handling.

Notes

Preview-only until sample reports are available.