refactor(store,tools): migrate IDs from UUID to bigserial int64

All internal entity lookups now use bigserial primary keys (int64) while
GUIDs are retained for external/public identification. Updated store
functions (TouchProject, UpdateThoughtMetadata, AddThoughtAttachment) to
query by id instead of guid, added GetThoughtByID, changed semanticSearch
and all tool helpers to use *int64 project IDs, and updated retry/backfill
workers to use int64 thought IDs throughout.

internal/generatedmodels/sql_public_agent_skills.go

@@ -9,10 +9,11 @@ import (
 
 type ModelPublicAgentSkills struct {
 	bun.BaseModel                    `bun:"table:public.agent_skills,alias:agent_skills"`
-	ID                               resolvespec_common.SqlUUID      `bun:"id,type:uuid,pk,default:gen_random_uuid()," json:"id"`
+	ID                               resolvespec_common.SqlInt64     `bun:"id,type:bigserial,pk,autoincrement," json:"id"`
 	Content                          resolvespec_common.SqlString    `bun:"content,type:text,notnull," json:"content"`
 	CreatedAt                        resolvespec_common.SqlTimeStamp `bun:"created_at,type:timestamptz,default:now(),notnull," json:"created_at"`
 	Description                      resolvespec_common.SqlString    `bun:"description,type:text,default:'',notnull," json:"description"`
+	GUID                             resolvespec_common.SqlUUID      `bun:"guid,type:uuid,default:gen_random_uuid(),notnull," json:"guid"`
 	Name                             resolvespec_common.SqlString    `bun:"name,type:text,notnull," json:"name"`
 	Tags                             resolvespec_common.SqlString    `bun:"tags,type:text,nullzero," json:"tags"`
 	UpdatedAt                        resolvespec_common.SqlTimeStamp `bun:"updated_at,type:timestamptz,default:now(),notnull," json:"updated_at"`