chore: remove more internal docs (beta, specs, debug, tester instructions)

- Removed 15 more internal docs from tracking
- AGENTS.md, SIDEBAR-SPEC, SPEC-008/011, beta docs, debug console, tester instructions
- All added to .gitignore
- Keeping: README, CONTRIBUTING, SECURITY, CHANGELOG, architecture docs, feature specs

.gitignore

@@ -106,3 +106,14 @@ docs/MODEL_SWITCHER_TESTPLAN.md
 docs/OVERNIGHT-SHIP-REPORT.md
 docs/QA/
 docs/security/
+AGENTS.md
+SIDEBAR-SPEC.md
+SPEC-*.md
+docs/BETA_*.md
+docs/DEBUG_CONSOLE.md
+docs/EMBEDDINGS-*.md
+docs/MODEL_SWITCHER_ROOT_CAUSE.md
+docs/POST-MERGE-PROTOCOL.md
+docs/TESTER_INSTRUCTIONS.md
+docs/RELEASE_CHECKLIST.md
+docs/DASHBOARD_QA.md