docs: reconcile release model to gated single-branch publish (delete PUBLISH_ON_MERGE)

[ptr727]

Reconciles the governance docs to the release model agreed with the maintainer, and clears two pre-existing inconsistencies.

Model (now documented)

A human PR merge never auto-publishes. A release is:

• a workflow_dispatch of main/develop (human-initiated), or
• a code-affecting bot push to main — the codegen App merges every Dependabot/codegen PR, so github.actor is the gate; a human merge/promotion to main skips, and an Actions-only bump is dropped by the paths filter, or
• a weekly schedule (Docker only, base-image refresh).

The decision is single-sourced in the plan job; every publish job gates on its output.

Changes

• AGENTS.md lines 13/29/52 (+ 54/56/224): the gated model; delete every PUBLISH_ON_MERGE reference (it was implemented in zero repos — pure removal).
• WORKFLOW.md §105, D4.1, D8.3, S5/S6/S7/S11: same model; reference publish-plan-task.
• Cleared the stale "branch matrix" language in AGENTS.md — WORKFLOW.md §105 already says the publisher builds the single trigger branch ("no branch matrix"); AGENTS.md hadn't caught up. (Flagged for your veto — this was the one item I wasn't 100% sure was stale; verified against every repo's publish-release.yml, which all build one branch.)

markdownlint + spec/validate.py clean; CRLF preserved. Codifies the rollout PRs (LanguageTags #255, Utilities #388, aiopurpleair #26, NxWitness #494, MediaTools #8, ESPHome-NonRoot #138) + the snippet #274.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Updates the repo's governance documentation to describe a gated, single-branch publish model (human merges do not auto-publish) and removes/updates legacy language tied to the prior release model.

Changes:

• Rewrites the documented release/publish triggers to a gated model (dispatch + bot push to main + scheduled Docker refresh).
• Removes PUBLISH_ON_MERGE references and updates surrounding rationale to match the new model.
• Updates upstream-version tracker and trace-scenario wording to align with the new gating rules.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 7 comments.

File	Description
AGENTS.md	Updates foundational and release-model governance text to the new gated publish model; removes legacy PUBLISH_ON_MERGE language.
WORKFLOW.md	Updates the release-model contract and scenarios to the gated single-branch publish model and references a planned single-source publish decision.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

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Pull request overview

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