docs: retire repo-mem MCP, migrate skills to .claude/skills, audit fixes

- Delete .mcp.json + .claude/rules/repo-mem.md; drop .repo-mem from .gitignore
- Remove repo-mem / substrate_score / repo_search references from all .md
- Move 15 EVOLV skills from .agents/skills/ to .claude/skills/ so they are
  auto-discovered by the Claude Code harness and invokable via the Skill tool
- Retire .agents/skills/evolv-orchestrator (duplicate of the subagent at
  .claude/agents/evolv-orchestrator.md); orchestrator lives as a subagent only
- Drop OpenAI-format agent yaml metadata from each skill (not needed for CC)
- Update CLAUDE.md, CONTRACTS.md, AGENTS.md to point at the new locations and
  disambiguate skills (.claude/skills/) vs subagents (.claude/agents/)
- Fix CLAUDE.md tick-loop wording (opt-in per-node, not a fixed 1000ms)
- Widen .claude/rules/ paths frontmatter so node-architecture and telemetry
  rules trigger on more relevant files; add frontmatter to flow-layout rule
- Bump CONTRACTS.md review date to 2026-05-19; add step 7 to the contract-
  change workflow (review example flows when topic usage changes)
- Bump nodes/generalFunctions pin (Home.md substrate_score reference removed)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.claude/skills/evolv-ot-edge-plc-integration/SKILL.md

@@ -0,0 +1,54 @@
+---
+name: evolv-ot-edge-plc-integration
+description: Engineer OT edge connectivity and PLC interoperability for EVOLV. Use when implementing or reviewing OPC UA/Modbus and similar integrations, namespace/tag mapping, quality/timestamp semantics, retry/reconnect behavior, and deterministic command/feedback contracts at the edge.
+---
+
+# EVOLV OT Edge PLC Integration
+
+## Mission
+Deliver reliable, deterministic edge protocol integration between EVOLV Node-RED nodes and PLC/SCADA systems.
+
+## Harness Execution Contract
+- Start from current integration topology, topic contracts, and protocol endpoints.
+- Define invariants before edits:
+  - command/feedback contracts remain deterministic
+  - reconnect/retry behavior is bounded and observable
+  - quality/timestamp semantics are preserved end-to-end
+- Validate with connection-loss and recovery evidence.
+
+## Scope
+- Edge/connector nodes (existing and new)
+- Topic mapping code in `nodes/*/src/`
+- Admin endpoints/config for connector behavior and credentials
+
+## Workflow
+1. Map PLC tags/NodeIds/registers to EVOLV message contracts.
+2. Define write acknowledgement and feedback confirmation rules.
+3. Implement reconnect/backoff/session handling.
+4. Enforce quality, timestamp, and stale-value semantics.
+5. Verify failover behavior and command idempotency.
+
+## Standards
+- Never assume connection continuity; model transient faults explicitly.
+- Keep protocol mappings versioned and auditable.
+- Separate transport errors from process-state errors.
+- Ensure secure defaults align with OT/IT security skill.
+
+## Test Expectations
+Cover:
+- disconnect/reconnect and session re-establish paths
+- duplicate/late/out-of-order message handling
+- read/write mapping correctness and unit conversion
+- safe behavior under degraded quality or timeout
+
+## Deliverables
+Return:
+- integration contract map (protocol <-> topic/payload)
+- retry/recovery strategy and limits
+- changed files/tests with failure-injection evidence
+- operational rollout risks and mitigations
+
+Decision interview triggers:
+- command authority or handshake behavior changes
+- protocol mapping breaks requiring migration
+- timeout/retry strategy changes affecting availability/safety