chore(git): stop tracking plan.md + resume.md; harden brain/settings ignores

plan.md/resume.md are now gitignored (git rm --cached; kept locally). Re-asserted the brain/ and config/settings.yaml ignores after an inline-comment edit briefly broke them. Note: both docs remain in existing git history - a scrub + README/CONTRIBUTING link fixes are follow-ups.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: vikast908

.gitignore

@@ -10,10 +10,18 @@ venv/
 dist/
 build/
 *.log
+# Generated projects + user data (brain/users/...) and local engine settings - never published
 brain/
 config/settings.yaml
 test_diagram.svg
 reseed.py
 
+# Local working docs: the design spec + the session journal stay private (durable decisions
+# also live in code + CHANGELOG.md). NOTE: both were tracked until now, so they remain in the
+# existing git history - a scrub is needed to remove them from the published repo, and
+# README/CONTRIBUTING linked to plan.md.
+plan.md
+resume.md
+
 # Playwright MCP browser artifacts (CI debugging)
 .playwright-mcp/