docs(fleet): record per-agent model switch in north star

Per-agent model selection (operator-configurable, webUI switch over the
existing roster model_hint plumbing) recorded as a decision of record so
it isn't lost. Also confirms orchestrator/enhancer run Claude Opus 4.8 in
Claude Code; only workers run pi/gpt-5.5.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

packages/db/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@mosaicstack/db",
-  "version": "0.0.4",
+  "version": "0.0.3",
   "repository": {
     "type": "git",
     "url": "https://git.mosaicstack.dev/mosaicstack/stack.git",

packages/mosaic/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@mosaicstack/mosaic",
-  "version": "0.0.47",
+  "version": "0.0.45",
   "repository": {
     "type": "git",
     "url": "https://git.mosaicstack.dev/mosaicstack/stack.git",