v1.9.11 — Spike Telemetry Commit + Runtime Cache Gitignore

Bookkeeping commit so the working tree is fully clean.

• Committed accumulated spike-result auto-telemetry (docs/superpowers/plans/spike-results/{P2,P3a,P4,P5a,P6,S1,S4}.md) that had been held as 'intentionally not committed' across sessions.
• Added .serena/ and .playwright-mcp/ to .gitignore so future sessions don't keep flagging runtime caches as untracked.

Both develop and main updated; tag pushed.