Clarify Hoplon agent-agnostic value

[justguy]

Summary

• describe Hoplon as an agent-agnostic repository boundary and context layer
• explain focused context, explicit edit scope, recovery, and review-evidence benefits
• document that any model can use Hoplon through an MCP-capable host
• distinguish estimated token telemetry and Hoplon-routed guarantees from billing claims or OS sandboxing

Verification

• git diff --check
• corresponding canonical-source proof: 105 focused assertions passed across context, MCP, public exports, and violating-edit recovery

Behavior changes

None. Documentation only.