refactor(FN-1317): rename remaining kb references to fn

- Update executor, triage, and merger prompt strings to identify the product as "fn"
- Align branch/worktree documentation examples with fusion/fn-* naming conventions
- Rename dashboard websocket attachment guard from __kbWebSocketsAttached to __fnWebSocketsAttached
- Refresh engine tests, dashboard utility comments, and TUI header text to remove stale kb wording

packages/dashboard/app/utils/projectDetection.ts

@@ -133,7 +133,7 @@ function getDefaultScanPath(): string {
 }
 
 /**
- * Sorts detected projects by likelihood of being a kb project.
+ * Sorts detected projects by likelihood of being a fn project.
  * Projects with .fusion/fusion.db are ranked higher.
  */
 export function sortDetectedProjects(projects: DetectedProject[]): DetectedProject[] {

packages/dashboard/app/utils/worktreeGrouping.ts

@@ -8,7 +8,7 @@ export interface WorktreeGroupData {
 
 /**
  * Extract a clean display name from a worktree path.
- * e.g. ".worktrees/KB-001" → "KB-001", "/path/to/kb/kb-001" → "kb-001"
+ * e.g. ".worktrees/FN-001" → "FN-001", "/path/to/fn/fn-001" → "fn-001"
  */
 export function getWorktreeLabel(worktreePath: string): string {
   // Take the last segment of the path