feat(tui): reduce visual noise and simplify navigation

[christso]

Summary

Addresses the three highest-priority proposals from #288:

• Compact workspace summary on re-loop: First menu entry shows the full p.note() workspace box; subsequent loops show a compact one-liner (Workspace: 0 project, 2 user, 6 marketplaces) to reduce visual clutter from repeated navigation
• Combined sequential spinners: Replaced double-spinner patterns (action spinner → sync spinner) with a single spinner that updates its message via .message(). Applied across all TUI flows: sync, skill toggle, plugin install/update/remove
• Compact skills browse: Each plugin entry now shows skill count and truncated preview in the hint field (17 skills: algorithmic-art, brand-guidelines, canvas-design +14 more) instead of repeating the full skill inventory on every entry

Test Plan

• bun test — 1053 pass, 0 fail
• bun run build — succeeds
• E2E: Launch ./dist/index.js, verify first menu shows full workspace note box
• E2E: Navigate into Plugins → Back, verify compact one-liner on second loop
• E2E: Skills → Browse marketplace skills, verify truncated skill lists with +N more
• E2E: Install a plugin, verify single spinner with changing message (no double spinner)
• E2E: Run sync, verify single spinner transitions from "project" to "user" message

Closes #288

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View logs

[christso]

E2E Validation Steps

Build and launch the TUI:

git checkout feat/288-reduce-tui-visual-noise
bun run build
./dist/index.js

1. Compact workspace summary

1. Observe the full workspace note box on first entry
2. Select Plugins → Back
3. Verify the menu now shows a compact one-liner like Workspace: 0 project, 2 user, 6 marketplaces instead of the full box

2. Single spinner

1. Select Plugins → + Add plugin → pick any plugin → choose scope
2. Verify a single spinner animates, changing message from "Installing plugin..." → "Syncing..." → "Installed and synced"
3. No second spinner should appear

3. Compact skills browse

1. Select Skills → Browse marketplace skills...
2. Verify each plugin entry shows a compact label with hint like (17 skills: algorithmic-art, brand-guidelines, canvas-design +14 more)
3. Verify NO multi-line Skills: ... list appears in the label