fix(agents): replace role profiles with poteto-agent only

[zhanfeng-alpha]

Why

Prompt softening left six role profiles available for routine fanout and supervisor gates. Replace them with one bounded poteto child and disable builtin discovery.

Companion routing change: cursor/plugins#363

Scope

• Add poteto-agent with implementation tools, no supervisor tool, and no nested delegation. Return blocked irreversible or product decisions without taking the action.
• Delete the six old overlay profiles. Installation backs up and removes their installed copies.
• Enable disableBuiltins and disable existing per-agent overrides except poteto-agent. Preserve other override fields.
• Route parents to poteto-agent only. Tiny known-mechanism fixes remain parent-inline.
• Update migration, reinstall, and discovery checks. The optional smoke selects poteto-agent.

Blast Radius

This host now discovers exactly poteto-agent. Backups preceded live installation. Existing children keep old prompts until respawn. Project settings can override user settings. No alc-options edits, deployment, jig refactor, or pi-subagents package rewrite.

Verification

bash scripts/check-overlay.sh passed, including all six retired-agent backups, removal, and reinstall idempotence.
bash scripts/check-conform-skills.sh passed.
PI_STACK_SMOKE=0 bash scripts/check-subagents.sh passed. Its discovery check calls the installed package directly and asserts exactly poteto-agent with the intended tool allowlist.
Live settings, installed profile, parent instructions, and poteto routes matched the source. Shell syntax and Git whitespace checks passed. Zero children or supervisor calls. The optional live smoke was not run.