chore(harness): make repository agent-ready

Add concise routed context, task-aware agent roles, focused skills, and structured learning promotion.\n\nUnify local development and workspace tooling, add layered test and E2E verification, harden MCP authentication, and gate deployment behind verification and explicit production promotion.

.agents/learnings/TEMPLATE.md

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+---
+id: YYYY-MM-DD-short-slug
+date: YYYY-MM-DD
+status: inbox
+scope: path or workflow
+evidence: command, test, or artifact
+review_after: YYYY-MM-DD
+---
+
+## Symptom
+
+Observable failure or friction.
+
+## Reproduction
+
+Exact bounded reproduction.
+
+## Cause
+
+Confirmed cause, not a hypothesis.
+
+## Remediation
+
+Proven correction.
+
+## Evidence
+
+Read-back, test, or other verification.

.agents/learnings/inbox/.gitkeep

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+

.agents/learnings/promoted/2026-08-27-migration-context-conflict.md

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+---
+id: 2026-08-27-migration-context-conflict
+date: 2026-08-27
+status: promoted
+scope: database migration instructions
+evidence: root and scoped agent context comparison
+destination: AGENTS.md and scripts/lint-harness.mjs
+review_after: 2027-02-27
+---
+
+## Symptom
+
+Root instructions prohibited remote migration application while scoped Supabase
+instructions authorized it.
+
+## Reproduction
+
+Compare the former root `AGENTS.md` migration rule with the former
+`apps/supabase/agents.md` migration section.
+
+## Cause
+
+Runtime-specific instruction files evolved independently without an executable
+consistency check.
+
+## Remediation
+
+Make root context authoritative, scope only additional local rules, and reject
+positive `apply_migration` instructions in the harness lint.
+
+## Evidence
+
+`npm run lint:harness` checks instruction consistency and the authoritative
+migration location.