refactor(studio): split the two files over the 600-line cap

[miguel-heygen]

What

Splits the two packages/studio files that are over the 600-line cap, so File size check goes green on main.

TimelineAutomationLane.tsx  674 -> 499
StudioRightPanel.tsx        609 -> 568

Pure code moves. No behavior change.

Why

File size check is currently failing on main, including on the v0.7.110 release commit.

The check is diff-scoped on a PR but full-scans packages/studio on push (ci.yml:858, and its own comment explains the split: walking the whole tree blamed every unrelated PR for pre-existing offenders). So a file that creeps over the cap passes its own PR and only fails after merge, where nobody owns it. Two have accumulated that way.

How

TimelineAutomationLane.tsx keeps the single-lane editor and gives up the track-level layer. ClipLaneRow, ClipAutomationLanes and TimelineAutomationLaneSlot move to a new TimelineAutomationLaneSlot.tsx, which is the name its test file already used, so the seam was effectively already drawn. The dependency runs one way, slot to lane, so there is no cycle. Two import sites updated.

StudioRightPanel.tsx gives up its props interface to a sibling StudioRightPanel.types.ts, re-exported so no consumer changes. I picked that cut deliberately over carving out a sub-component: two in-flight branches (#3291, #3292) touch this file and both are based on a 556-line copy of it, so they will conflict on rebase regardless. Keeping the cut in the interface block, which is the part that changes least, keeps their conflicts away from the component body.

Both files also shed the imports that left with the moved code.

Test plan

• Unit tests added/updated
• Manual testing performed
• Documentation updated (if applicable)

No new tests: these are moves, and the existing TimelineAutomationLaneSlot.test.tsx already covers the extracted component (6 tests, still green against its new home).

Ran the CI rule's own full-scan branch locally over the 681 tracked packages/studio source files: no file over 600, exit 0.

• Studio suite: 2790 passed across 226 files
• tsc --noEmit on packages/studio: clean
• oxlint / oxfmt: clean

Note for #3291 and #3292

Both touch StudioRightPanel.tsx from a 556-line base. After this lands their rebase picks up the split file. The props interface moved out wholesale to StudioRightPanel.types.ts; the component body is otherwise untouched, so conflicts should be confined to imports.