[CTX-1335] fix(ui): evict only bounds-only tweens and carry painted bounds on re-arm

[Xuepoo]

Summary

Follow-up to #2231 for the two CodeRabbit inline findings that were not part of
the squashed merge (3ec20bed, main 8da9df0d). This is a fix-only branch; it
does not re-introduce the panel-geometry feature.

Findings addressed

1. Carry painted bounds forward when a gesture re-arms the ring. PanelAnimator::trigger previously dropped an in-flight bounds tween for Move/Resize/Drag and created a ring entry with bounds: None, so the next present started from the last committed target instead of the painted frame. Continuous Alt+drag could snap on every update. The replacement entry now carries the current interpolated frame plus the previous destination; the next present retargets from the painted bounds. Close behavior is unchanged.
2. Evict only bounds-only tweens at the shared budget. drop_one_bounds selected any entry with bounds, including a reused Move ring or the Alt-drag Drag entry, deleting an accepted ring fade. It now evicts only bounds.is_some() && !ring entries; when none exists the trigger is refused, preserving the documented ring priority.

Scope

• crates/bitty-runtime/src/runtime/animations.rs — the two fixes and two animator regressions.
• crates/bitty-runtime/tests/panel_animations.rs — consecutive Alt-drag continuity regression.

Diff vs origin/main: 2 files, +159/−7. No other product code.

Verification

• cargo fmt --all -- --check — pass
• RUSTFLAGS="-D warnings" cargo clippy -p bitty-runtime -p bitty-ui --all-targets --locked — pass
• cargo nextest run -p bitty-runtime --locked — 2519 passed, 1 skipped
• cargo test -p bitty-runtime --lib runtime::animations:: --locked (debug, overflow checks) — 22 passed
• cargo check --target x86_64-pc-windows-gnu --workspace --all-targets --locked — pass

Regression proof: removing the carried bounds makes consecutive_alt_drag_updates_carry_painted_bounds_forward snap to the previous target; restoring the old eviction predicate makes overflow_preserves_a_ring_entry_that_hosts_bounds delete the drag ring. Both fail without the fixes.

Priority: P2 | Area: area:ui | Labels: fix,P2,area:ui | Milestone: v0.1.0 | RFC: RFC-0002 panel animation contract | Task: CTX-1335

Summary by CodeRabbit

• Bug Fixes
  • Prevented panels from visually jumping when movement, resizing, or dragging animations are retargeted mid-transition.
  • Preserved ring animations when clearing older bounds-only animations.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

• Configuration used: Repository UI (base), Organization UI (inherited)
• Review profile: CHILL
• Plan: Advanced
• Run ID: 4d1b701d-42e1-4c78-8dc1-4fe87e0b1193

📥 Commits

Reviewing files that changed from the base of the PR and between 8da9df0 and a9a0251.

📒 Files selected for processing: 2

• crates/bitty-runtime/src/runtime/animations.rs
• crates/bitty-runtime/tests/panel_animations.rs

Included review availability: This review used your included allowance. Your plan provides up to 1 included review per hour; 0 remain after this review.

📝 Walkthrough

Panel animation restarts now carry forward interpolated bounds for Move, Resize, and Drag transitions. Bounds eviction now preserves ring animations that host bounds. Tests cover retarget continuity and eviction behavior.

Changes: Panel bounds animations

Layer / File(s)	Summary
Carry bounds across gesture restarts crates/bitty-runtime/src/runtime/animations.rs, crates/bitty-runtime/tests/panel_animations.rs	Move, Resize, and Drag restarts carry forward the current interpolated bounds and previous destination. New ring animations retain carried bounds. A regression test checks continuity during consecutive Alt-drag updates.
Preserve ring animations during bounds eviction crates/bitty-runtime/src/runtime/animations.rs	Bounds eviction selects unfinished entries without a ring. A test checks that eviction removes a separate bounds-only tween while preserving a drag ring that hosts bounds.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

Merge Risk: ⚪ Minimal · up to a9a02

This change keeps panel animations continuous when a gesture restarts and stops budget eviction from removing ring animations. No concrete merge-blocking risk was found.

Pre-merge checks: 5

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely identifies both main changes: bounds-only tween eviction and carrying painted bounds when re-arming animations.
Docstring Coverage		Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 8 functions across 2 files.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

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