fix: cap distiller startup scan and switch to formal SDK module dependency

- replace vendored third_party/homeagent-sdk with formal module dependency
- keep canonical SDK via go.mod pinned commit
- optimize distiller startup loading to stream recent raw records only
- parse timestamps correctly and cap startup load to 5000 records
- remove quadratic string building in raw record parsing
- restore fast startup while preserving memory pipeline

third_party/homeagent-sdk/hack/plugin-dev/templates/plugin.json.tmpl

@@ -1,10 +0,0 @@
-{
-  "name": "{{.Name}}",
-  "version": "{{.Version}}",
-  "description": "{{.Description}}",
-  "author": "{{.Author}}",
-  "license": "MIT",
-  "entry": "plugin.so",
-  "min_version": "1.0.0",
-  "tags": ["{{.Name}}"]
-}