Blog: v0.19.0 release, OpenClaw plugin, and agent skills posts

[bm-clawd]

Three blog posts for the marketing site:

1. v0.19.0 Release — Leads with semantic search, covers schemas, cloud routing, and QoL improvements
2. OpenClaw Plugin — Opens with the amnesia problem, shows two-line install, explains the bidirectional plain-text difference
3. Agent Skills — Frames as tools vs habits, walks through all nine skills with pick-what-you-need section

All follow the voice from the Drew Nellins collabs: opinion-driven, concrete, no hype, soft BM pitch at the end.

Created a new 9.blog/ content section with navigation.

[bm-clawd]

Moved to basicmemory.com repo — see https://github.com/basicmachines-co/basicmemory.com/pull/26