[codex] Add aggregate constraint validation

[greenthree]

What changed

• add conservative statement/Validator reconciliation for multi-case aggregate limits
• report matched, statement-only, Validator-only, dynamic, and mismatch states through lint/report
• add the Agent derivation contract for T_max, aggregate work budgets, joint feasibility, and calibration
• route the new aggregate-limit checks through the Skill and verification-mode sealing gates
• update the npm release inventory, documentation, changelog, and package versions to 0.6.5

Why

Multi-case problems can state a total-size limit without enforcing it in the Validator, or enforce a different limit than the statement. That makes the intended complexity and official data contract unreliable. This change adds a conservative automated reconciliation layer while keeping algorithmic complexity analysis and final Validator review explicitly human/Agent-owned.

User impact

Authors now receive structured aggregate-constraint diagnostics in lint and report. The Skill also guides authors to derive a safe T_max and cumulative-size limit from test demand, per-case work, I/O, fixed costs, joint worst cases, and the existing accepted_max_time * 3 <= TL calibration rule.

Validation

• npm run check: 560 passed, 26 skipped
• npm run pack:check: probhub 213 files, probhub-skill 5 files
• npm package tests: 18 passed
• Skill quick validation passed
• git diff --check passed
• current Core against the local phtest workspace: 9 problems, 0 errors
• L01 and L06 aggregate constraints detected as matched
• three same-model forward tests covered linear/n log n, fixed per-case costs, graph limits, and joint-feasibility rejection