Add composability axis to meta_engine filter_score judge prompt

Add 'COMPOSABLE' as a 7th evaluation axis in the FILTER_SYSTEM prompt (currently lines ~18-46 define 6 axes: SPECIFIC, FALSIFIABLE, SOLO-FEASIBLE, LOW BLAST, REVERSIBLE, EVIDENCE). New axis text: 'COMPOSABLE — Can this proposal be implemented in parallel with other likely co-pending proposals without cross-file conflict or logical contradiction? Assess: major concern if it modifies the same function block or variable as another proposal currently in the meta pipeline; minor concern if it requires sequential ordering (must be implemented before or after a peer); no concern if target_files and proposed_diff scope are fully independent. Base assessment on target_files array overlap and proposed_diff scope description.' Also extend the axis_concerns enum in the JSON schema section (~line 150) to include 'composability' alongside the existing 6 values.

When two proposals both target the same file and modify overlapping function blocks, the judge flags composability=major on at least one. Across 30 meta_filter_score runs (current observed volume), this surfaces implementation ordering conflicts before they reach Commander approval, preventing rollback-requiring sequential deploys.

Submit two test meta-proposals that both specify target_files=['hypothesis_engine/moves/filter_score.js'] and both describe modifying the same FILTERS array entry. If the judge returns composability with severity='no_concern' on both, the axis is not detecting the conflict. If at least one receives severity='major', the axis is functional.

Rejected by filter_score. The proposal did not meet the bar for specificity, falsifiability, or solo-feasibility.