Keep long slug IDs compact and copyable

[kentwelcome]

Keep long slug IDs from squeezing task titles while making complete identifiers easy to copy.

What changed

• Bound ID columns using responsive Unicode display-cell widths.
• Ellipsize long IDs while preserving title space and short-ID alignment.
• Copy complete IDs on double-click through OSC 52.
• Show transient copy feedback and document terminal support.

Evidence

• Spacetop library: 385/385 passed; Spacetop core: 188/188 passed.
• make lint passed; an independent CJK copy probe returned the full slug.

---

074

[Copilot]

Pull request overview

This PR improves task-list readability for workflows with long slug IDs by capping the ID column using terminal display-cell widths, rendering long IDs with ellipsis, and adding a mouse double-click action to copy the full underlying ID via OSC 52 (with transient footer feedback and updated help/docs).

Changes:

• Compute a responsive ID column width (4–20 cells) using Unicode display widths and ellipsize overlong IDs while preserving a minimum title width.
• Add double-click-on-ID hit-testing to queue a “copy full ID” intent and emit OSC 52 at the terminal boundary.
• Add UI feedback (“ID copied” / “ID copy failed”) and update docs + tests for layout, Unicode width behavior, and copy feedback.

Reviewed changes

Copilot reviewed 13 out of 14 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
README.md	Documents double-click ID copy behavior and OSC 52 terminal requirements.
crates/spacetop/src/ui/tests/task_list.rs	Adds layout/Unicode width tests for the responsive ID column and footer copy feedback expiration.
crates/spacetop/src/ui/tests/chrome.rs	Asserts help popup contains the new double-click copy hint.
crates/spacetop/src/ui/mod.rs	Threads copy feedback into overview rendering so footer can show status.
crates/spacetop/src/ui/list.rs	Implements responsive ID width calculation and Unicode-aware ellipsizing; records ID-column rect for hit-testing.
crates/spacetop/src/ui/help.rs	Adds “Double-click ID” help line.
crates/spacetop/src/ui/footer.rs	Adds transient copy success/failure hint rendering.
crates/spacetop/src/lib.rs	Emits OSC 52 sequences (base64) when a pending copy intent is drained; adds OSC52 unit tests.
crates/spacetop/src/app/overview.rs	Stores a new render-fact (id_column_rect) for ID hit-testing.
crates/spacetop/src/app/mouse.rs	Adds ID-cell hit-testing and double-click tracking that triggers a copy action.
crates/spacetop/src/app/keys.rs	Introduces OverviewKeyAction::CopyId to route copy intents through the app boundary.
crates/spacetop/src/app.rs	Adds copy intent + timed feedback state; wires overview mouse handling with timing/candidate tracking.
crates/spacetop/Cargo.toml	Adds base64 and unicode-width dependencies.
Cargo.lock	Locks new dependency entries.