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/sdk/memory.go

@@ -1,60 +0,0 @@
-package sdk
-
-// MemoryAPI provides access to the graph memory (entity-relation store).
-type MemoryAPI interface {
-	Recall(query []string, depth int) ([]Entity, []Relation, error)
-	Commit(triples []Triple) error
-	Introspect() (map[string]interface{}, error)
-	MergeEntities(source, target string) (int, error)
-	Purge(criteria map[string]string, mode string) (int, error)
-}
-
-// Entity represents a named entity in the knowledge graph.
-type Entity struct {
-	Name         string `json:"name"`
-	Type         string `json:"type"`
-	MentionCount int    `json:"mention_count"`
-}
-
-// Relation represents a relationship between two entities.
-type Relation struct {
-	SourceName   string `json:"source_name"`
-	TargetName   string `json:"target_name"`
-	RelationType string `json:"relation_type"`
-}
-
-// Triple represents a subject-relation-object triple for the knowledge graph.
-type Triple struct {
-	Subject  string `json:"subject"`
-	Relation string `json:"relation"`
-	Object   string `json:"object"`
-}
-
-// TextMemoryAPI provides access to chronological text event storage.
-type TextMemoryAPI interface {
-	Append(evt TextEvent) error
-}
-
-// TextEvent represents a single text memory event.
-type TextEvent struct {
-	Role      string `json:"role"`
-	Content   string `json:"content"`
-	Timestamp int64  `json:"timestamp"`
-	Channel   string `json:"channel,omitempty"`
-}
-
-// DocMemoryAPI provides access to the document vector store.
-type DocMemoryAPI interface {
-	Query(text string, topK int) []*Doc
-	Insert(doc *Doc) error
-	Remove(id string)
-	Stats() map[string]interface{}
-}
-
-// Doc represents a document in the document store.
-type Doc struct {
-	ID      string  `json:"id"`
-	Title   string  `json:"title"`
-	Content string  `json:"content"`
-	Score   float64 `json:"score,omitempty"`
-}