feat: initial alpha scaffold — FastAPI + MCP + pgvector

Implements v0.0.1 of OpenBrain:

- FastAPI REST API (capture, search, recent, stats) with Bearer auth
- MCP server (streamable HTTP at /mcp) exposing all 4 tools
- pgvector schema (vector(1024) for bge-m3)
- asyncpg connection pool with lazy init + graceful close
- Ollama embedding client with fallback (stores thought without vector if Ollama unreachable)
- Woodpecker CI pipeline (lint + kaniko build + push to Gitea registry)
- Portainer/Swarm deployment compose
- Mosaic framework files: AGENTS.md, PRD.md, TASKS.md, scratchpad

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.woodpecker/build.yml

@@ -0,0 +1,49 @@
+when:
+  - event: push
+    branch: main
+  - event: tag
+
+variables:
+  - &registry git.mosaicstack.dev
+  - &image git.mosaicstack.dev/mosaic/openbrain
+
+steps:
+  lint:
+    image: python:3.12-slim
+    commands:
+      - pip install ruff --quiet
+      - ruff check src/
+      - ruff format --check src/
+
+  build:
+    image: plugins/kaniko
+    settings:
+      registry: *registry
+      repo: *image
+      tags:
+        - sha-${CI_COMMIT_SHA:0:8}
+        - latest
+      username:
+        from_secret: GITEA_USERNAME
+      password:
+        from_secret: GITEA_TOKEN
+      build_args:
+        - BUILDKIT_INLINE_CACHE=1
+    when:
+      - event: push
+        branch: main
+
+  build-tag:
+    image: plugins/kaniko
+    settings:
+      registry: *registry
+      repo: *image
+      tags:
+        - ${CI_COMMIT_TAG}
+        - sha-${CI_COMMIT_SHA:0:8}
+      username:
+        from_secret: GITEA_USERNAME
+      password:
+        from_secret: GITEA_TOKEN
+    when:
+      - event: tag