task(ceremony): reckon as explicit ceremony element in begin and plan

[pentaxis93]

Summary

Part of #191. Reckon is referenced in begin and plan preambles but not invoked procedurally. Agents following the procedures can frame sessions and surface constraints without first-principles verification.

Scope

File	Change
protocols/begin/PROTOCOL.md	Add reckon step to Phase 0c (Frame)
protocols/plan/PROTOCOL.md	Add reckon step to phase-2-resolve-intent

Acceptance Criteria

• begin Phase 0c invokes reckon to verify the issue's constraints before deriving the Four Touches — an agent cannot commit to a session frame built on unverified assumptions
• plan phase-2-resolve-intent invokes reckon to verify constraints before surfacing them from the codebase — constraints reflect actual need, not accidental architecture
• Cross-references updated where missing
• Pattern matches the ceremony integration established in decompose (feat(decompose): make reckon invocation explicit in ceremony #186) and survey

Dependencies

None — independent of the other tasks in #191.

Evidence

• begin/PROTOCOL.md lines 76-93: Frame derives Four Touches from issue body without constraint verification
• plan/PROTOCOL.md lines 84-85: "Surface constraints from the codebase" without verifying those constraints reflect actual need
• orient/SKILL.md line 70: "reckon is not step-one-once. New generative work mid-session requires reckoning anew."