docs: add strict bot policies (non-loop) + update trigger workflow

[hlin99]

Changes:

• Add bot/ directory with strict policies (non-loop mode: bot never merges)
• BOT_POLICY, AUTHOR_POLICY, REVIEW_POLICY, ENTRY
• Update trigger-integration.yml to fire on pull_request (not just release)
• Move old BOT_POLICY.md to bot/BOT_POLICY_LEGACY.md for reference

[hlin99-Review-Bot]

LGTM. Reviewed all 6 changed files.

Summary:

• bot/ directory structure with split policies (BOT_POLICY, AUTHOR_POLICY, REVIEW_POLICY, ENTRY) is clean and well-organized.
• Legacy BOT_POLICY.md correctly preserved as BOT_POLICY_LEGACY.md for reference.
• Workflow change: adding pull_request trigger and switching to INTEGRATION_TOKEN for cross-repo dispatch is reasonable. The conditional logic for PR vs release events is correct.
• No code changes, no security concerns, no test impact.
• CI all green (lint, test 3.10/3.11/3.12, build, trigger).

One note: bots currently reading BOT_POLICY.md from repo root will need to update their paths to bot/BOT_POLICY.md after this merges.

[hlin99-Review-BotX]

hlin99-Review-BotX — reviewing commit 118a470

Issues Found

1. Broken reference: DESIGN_PRINCIPLES.md does not exist

• bot/ENTRY.md (line 15) lists DESIGN_PRINCIPLES.md as mandatory required reading (#4).
• bot/AUTHOR_POLICY.md (line 15) links to [DESIGN_PRINCIPLES.md](DESIGN_PRINCIPLES.md) for architecture constraints.
• bot/BOT_POLICY.md (line 49) links to [DESIGN_PRINCIPLES.md](DESIGN_PRINCIPLES.md).

This file is not included in the PR and does not exist on main. All three references are broken links. Either include the file in this PR or remove the references until it exists.

Everything else looks good

• Workflow change in trigger-integration.yml is clean: adds pull_request trigger, switches to INTEGRATION_TOKEN (cross-repo dispatch needs a PAT, not GITHUB_TOKEN), and handles both event types correctly.
• Policy split across bot/BOT_POLICY.md, AUTHOR_POLICY.md, REVIEW_POLICY.md, ENTRY.md is well-organized.
• Legacy policy preserved as bot/BOT_POLICY_LEGACY.md — good for reference.
• Note: ensure existing bot crons that read root BOT_POLICY.md are updated to read from bot/ after merge.