release-train: staging -> main

[LukasWodka]

Automated promotion by the release train (RFC-0008 D14). Head is the train-managed release-train/to-main branch (a mirror of staging), so it never collides with a human PR. Merged only when the fr-gate is green.

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Note

Low Risk
Changes are workflow callers and synced engineering prose; no product runtime code. Bugbot runs add CI load and may show red advisory checks on some PRs without blocking merge.

Overview
This promotion bundles CI workflow changes and a synced org-standards block in CLAUDE.md.

Bugbot (fleet step 2): Adds bugbot-gate-caller.yml, a thin caller to tracebloc/.github’s reusable bugbot-gate.yml on PR open/sync/ready-for-review, with concurrency and read-only permissions. It runs the bugbot / review check as advice only—branch protection and repo-inventory are intentionally not updated in this PR (required follow-up in .github).

FR gate: Extends fr-gate-caller.yml with the edited pull_request type so the gate re-runs when the PR base branch changes, avoiding a stale gate / gate verdict after retargets.

CLAUDE.md: Replaces hand-waved branch-model exceptions with read repo-inventory.yml, documents the unprotected-develop trap, adds git reap / branch_owner.py cleanup guidance, a “fix the class, not the instance” quality rule, and clarifies bug-kanban automation vs manual moves in three repos.

^{Reviewed by Cursor Bugbot for commit 2779e85. Bugbot is set up for automated code reviews on this repo. Configure here.}

[LukasWodka]

bugbot run

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{❌ Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, enable autofix in the Cursor dashboard.}

^{Reviewed by Cursor Bugbot for commit 2779e85. Configure here.}

[LukasWodka]

Promoted with 1 open Medium/Low Bugbot finding(s), per the severity policy in release-train's README (High stops the line; Medium/Low are recorded and ship, at both hops):

Caller does not skip bot PRs

This is a third look at twice-reviewed code -- it passed per-feature review and functional review on the source branch before the promotion. Fix forward on develop if any is real.

What the train did with each:

• Caller does not skip bot PRs - filed as https://github.com/tracebloc/backend/issues/2647, thread resolved by the train.