[felipebalbi]

Summary

Adds an opt-in --boards flag to paavo-cli admin purge that, in addition to the existing jobs/logs/build-cache/artifacts reset, wipes the entire board inventory — behind a [y/N] confirmation that defaults to No and is bypassable with --yes/-y.

• Daemon: POST /admin/purge?boards=true runs DELETE FROM board inside the same DB-lock scope as the existing job truncation (FK-safe: job.board_id is the only referrer and jobs are deleted first; schedule doesn't reference boards), then refreshes the in-memory inventory cache after the lock is dropped. The pre-existing 409 in-flight gate still runs first.
• Default unchanged: no flag / boards=false preserves boards exactly as before (backward-compatible wire — no-query callers unaffected).
• CLI: AdminOp::Purge gains --boards and --yes; a declined/empty/EOF answer prints purge aborted and exits 0 without any HTTP call.

Spec: docs/superpowers/specs/2026-06-17-purge-all-boards-design.md
Plan: docs/superpowers/plans/2026-06-17-purge-all-boards.md

Test Plan

• cargo fmt --all -- --check clean
• cargo clippy --workspace --all-targets -- -D warnings clean
• cargo test --workspace green (1 hardware test #[ignore])
• Daemon: ?boards=true deletes boards + clears inventory cache; ?boards=false preserves; ?boards=true still 409s when a job is running (crates/paavod/tests/api_admin.rs)
• CLI: declined/empty answer aborts without a network call; --yes bypasses the prompt; --help lists --boards/--yes (crates/paavo-cli/tests/cli_admin_purge.rs, cli_help.rs)