docs: configure GitHub for squash merge and auto-run workflows on Draft PRs

[kitelev]

Summary

Configures GitHub repository settings for:

1. Squash merge only - all PR commits combined into single commit on main
2. Auto-run workflows on Draft PRs - CI runs without manual approval
3. Linear history - enforced via required_linear_history + squash merge

Changes Made

GitHub API Configuration

• ✅ Enabled squash merge (allow_squash_merge: true)
• ❌ Disabled rebase merge (allow_rebase_merge: false)
• ❌ Merge commits already disabled
• ✅ Auto-merge enabled (no changes needed)

Workflow Changes

File: .github/workflows/ci.yml

• Added explicit PR event types: [opened, synchronize, reopened, ready_for_review]
• Now triggers on Draft PRs automatically

Documentation

New file: .github/GITHUB_SETTINGS.md

• Complete documentation of all GitHub settings
• Verification commands for checking configuration
• Rollback instructions
• Workflow examples

Updated: CLAUDE.md

• Corrected merge strategy documentation (squash merge creates NEW commit, not git rebase)
• Updated workflow steps to include manual rebase when main changes
• Clarified that strict: true requires manual branch updates
• Fixed step numbering (11 → 12 steps)

How Squash Merge Works

What actually happens:

Before:
main:     A---B---C
feature:      \---D---E---F

After squash merge:
main:     A---B---C---G  (G = NEW commit with D+E+F changes)

Key points:

• GitHub creates NEW commit on main (not git rebase)
• All branch commits combined into single commit
• Manual git rebase origin/main needed if main changed (strict mode)
• Linear history maintained (no merge commit branches)

Verification

# Check merge settings
gh api repos/kitelev/exocortex-obsidian-plugin | \
  jq '{allow_squash_merge, allow_rebase_merge, allow_merge_commit}'

# Expected output:
# {
#   "allow_squash_merge": true,
#   "allow_rebase_merge": false,
#   "allow_merge_commit": false
# }

# Check branch protection
gh api repos/kitelev/exocortex-obsidian-plugin/branches/main/protection | \
  jq '{required_linear_history, required_status_checks}'

Test Plan

• Workflow changes tested (this PR will verify auto-run on PR creation)
• GitHub API settings applied successfully
• Documentation created and reviewed
• CI checks pass (automatic verification)
• Merge via squash (verifies new merge strategy)

References

• GitHub API: Repository settings
• GitHub Actions: PR trigger events
• CLAUDE.md: Development workflow guidelines

[Copilot]

Pull Request Overview

This PR updates the repository's merge strategy from rebase-only to squash-merge-only, aligning with GitHub best practices for maintaining linear history while simplifying the merge process. The changes document the new workflow and update CI configuration to support draft PRs.

Key changes:

• Switched from --rebase to --squash merge strategy in CLAUDE.md workflow documentation
• Added explicit PR event types to CI workflow to trigger on draft PRs
• Created comprehensive GITHUB_SETTINGS.md documenting all repository configurations

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
CLAUDE.md	Updated workflow steps and merge strategy documentation from rebase to squash merge, added manual rebase step before merge
.github/workflows/ci.yml	Added explicit PR event types to enable CI runs on draft PRs
.github/GITHUB_SETTINGS.md	New comprehensive documentation of all GitHub repository settings, merge strategies, and configuration details

Comments suppressed due to low confidence (1)

CLAUDE.md:296

• Documentation still refers to 'rebase-only' strategy, but the PR changes the merge strategy to squash-only. This should be updated to reflect the new strategy: 'Linear history REQUIRED (squash-merge-only, no merge commits)'.

- ✅ Linear history REQUIRED (rebase-only, no merge commits)

[Copilot]

Documentation states 'Kept rebase merge enabled' but line 35 shows allow_rebase_merge: false and line 44 states 'Regular rebase disabled'. This is contradictory. The documentation should state 'Disabled rebase merge' to match the actual configuration.

Suggested change

	- Kept rebase merge enabled
	- Disabled rebase merge