feat(agent): add pi print mode

[codeaholicguy]

Summary

• add durable Pi print agents backed by Pi JSON event mode
• persist and resume provider session UUIDs through the generalized print-agent store
• wire Pi creation, send dispatch, list, detail, and console visibility into the agent CLI

Design

Source: docs/ai/design/2026-08-17-feature-pi-print-mode.md

Pi CLI behavior is grounded in the installed @earendil-works/pi-coding-agent documentation and source. The open Codex print-mode PR #148 was used only as a read-only consistency reference.

Validation

• npm test (all 6 projects; agent-manager 552 tests, CLI 986 tests)
• npm run build (all 6 projects)
• npm run lint (0 errors; existing warnings only)
• pure Pi protocol coverage: 100% statements, branches, functions, and lines with enforced thresholds
• npx ai-devkit@latest lint --feature pi-print-mode

Risks

No known blockers. Store schema v2 retains strict legacy Claude record reads; Pi session IDs are late-bound under run ownership and validated for provider uniqueness.

[codeaholicguy]

Rebased onto current origin/main and adapted Pi print mode to the durable-agents architecture.

• Pi provider modules and tests now live under src/durable/ / __tests__/durable/.
• Uses shared DurableAgentRepository + SQLite durable_agents/CAS ownership; the obsolete file-store generalization and legacy import work were dropped.
• Extends the durable provider union to claude | pi; Pi creation uses the repository-assigned UUID with pi --mode json --session-id, then resumes via --session.
• agent start --type pi --mode print and persisted-provider send dispatch are wired with minimal shared CLI changes.
• Lifecycle docs were updated for the durable/SQLite design.

Verification: npm ci, full workspace build/test/lint, Nx typecheck, and feature-doc lint all pass. All PR CI and E2E checks are green.

[codeaholicguy]

Rebased onto origin/main including #190. Pi durable start now uses --mode durable, retains --type pi support, and the old --mode print spelling is rejected by the shared validation. Updated the focused CLI test and lifecycle docs. Full local build/test/lint/typecheck/doc-lint and all PR CI/E2E checks are green.