fix(protocol): require session close before branch merge

[leadsolutions-mike]

Closes #2.

Adds an explicit branch ordering rule to the protocol: all session-close artifacts must be committed on the feature branch before the PR is opened, not written to the default branch after merge.

Changes

.agents/PROTOCOL_RULES.md — kernel v2.0.0 → v2.0.1

• New ### Branch ordering rule (v2.0.1+) subsection in §P3, before the verification step
• New checklist item in the handoff schema: - [ ] Session-close state written on the feature branch before the PR is opened (when substrate uses pull requests — see §M-git-6)

.agents/modules/git-substrate.md — v1.1.0 → v1.2.0

• New §M-git-6 — Session close ordering before PR merge after existing §M-git-5
• Includes interaction note clarifying how §M-git-6 relates to the direct-commit allowance in §M-git-1

README.md — version history entry for 2.0.4 (per §M-git-3)

No template/ files. Single focused commit on a clean branch from current main. Replaces #15.

Test plan

• CI passes (state-validation + readme-sync workflows)
• PROTOCOL_RULES.md shows Version: 2.0.1
• git-substrate.md shows Version: 1.2.0 with §M-git-6 present
• README has 2.0.4 as the first version history entry

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Contributed by @leadsolutions-mike as external collaborator.

[mmilanez]

Thanks for opening the clean replacement PR. The diff now looks focused and reviewable.

Before final review/merge, please handle two small PR-maintenance items on your side:

1. Update/rebase the branch against current main; GitHub still reports the PR as BEHIND.
2. Fix the PR description formatting so GitHub recognizes Closes #2. Right now the issue is not linked in the PR metadata, likely because the body contains escaped \n text instead of normal Markdown line breaks. Please put Closes #2 on its own normal Markdown line.

After those two updates and passing CI, this should be ready for final review.

[mmilanez]

Approved. Clean replacement PR, focused v2-compatible diff, required checks passing, and issue #2 linked.