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

CHANGELOG.md

@@ -1,5 +1,9 @@
 **July 2026**
 
+A routine can now include the same exercise more than once — swipe right on an exercise to duplicate it for interval-style segments.
+
+Exercises can now be renamed per routine, like "Warmup Walk" for a treadmill segment, while their animated figure and guide still follow the original exercise.
+
 A new Running exercise joins the library with its own animated stride figure.
 
 Exercise figures no longer glitch mid-rep — bars, hands, and feet stay planted instead of snapping or windmilling.