Let routines rename exercises and repeat them for interval segments

An exercise's name is now a per-routine display name: a new optional
libraryName on ExerciseDocument (snapshotted onto WorkoutLogDocument at
plan time) keeps the link to the bundled library exercise, and every
figure/info/cue lookup resolves libraryName ?? name. Deliberately not
schema-bumped — an older app dropping the key only strands the
figure link, same rationale as activityType. Cache schema bumped to 9
for the new columns.

The picker no longer filters out exercises already in the routine
(an "×N" badge marks them instead), exercise rows gain a leading
Duplicate swipe that clones an entry in place, and the edit sheet gets
a Name field with the library exercise shown read-only above it.

Claude-Session: https://claude.ai/code/session_01H8VxUX4ckjU3vRF5M4L5FV

Workouts Watch App/Views/WorkoutLogListView.swift

@@ -166,7 +166,8 @@ struct WorkoutLogListView: View {
             currentStateIndex: 0,
             status: WorkoutStatus.notStarted.rawValue,
             notes: nil,
-            date: doc.start
+            date: doc.start,
+            libraryName: exercise.libraryName
         )
         newLog.touch()   // a fresh log carries a definite creation time for the merge
         doc.logs.append(newLog)