feat(skills): add deep-plan + super-plan planning skills

[Number531]

Summary

Tracks two planning skills that were previously local-only / untracked in the working tree, bringing them onto main alongside the rest of the skills catalog.

• deep-plan (.claude/skills/deep-plan/) — a dynamic Workflow harness: 5 parallel Explore mappers (edit-sites, blast-radius, smoke-surface, integration-surface, conventions-arch) → plan synthesis → 5-lens adversarial audit with per-finding verification, cross-lens dedup, keep-best scoring, and stop-on-no-progress. Returns the best-scoring plan + an honest audit trail. Read-only.
• super-plan (.agents/skills/super-plan/) — prose planning skill that writes a phased implementation-*.md spec into a pending-updates/ folder.

Review fixes included (deep-plan.workflow.js)

This PR also folds in three corrections from a code review of the workflow:

1. Null-synthesis guard — if plan synthesis dies, fail loud instead of serializing "null", burning a full audit loop, and returning plan: null as a real artifact. Mirrors the existing map-phase degraded handling.
2. Verifier drop-safety — a finding is rejected only on an explicit real === false verdict, never on an omitted one, so a partial verifier response can't silently suppress a genuine critical and surface the plan as falsely converged/sound.
3. Grounding accuracy — removed the phantom src/utils/sdkRouting.js (no such file) → real files; pinned src/schemas/toolEnvelopes.js.

Notes

• deep-plan.workflow.js REPO_ROOT defaults to a machine-absolute path (/Users/ej/Super-Legal/...) but is overridable via args.repoRoot — documented in the SKILL.md.
• node --check passes on the workflow script.

🤖 Generated with Claude Code

[Number531]

Closing — keeping deep-plan / super-plan skills local-only for now. Will revisit.