docs: document tab, pane and project-group features

[artyomsv]

Summary

Brings the README, docs/ and the GitHub Pages site up to date with the four features released as v1.76.0–v1.79.0:

• tab-bar wheel scroll (feat(tui): scroll the tab bar with the mouse wheel #228);
• the tab context menu (feat(tui): add a tab context menu with rename, colour and move to project #229);
• moving panes between tabs, tab layouts and Alt+drag (feat(tui): move panes between tabs and rearrange a tab's layout #230);
• project groups in the sidebar (feat(tui): group projects in the sidebar and highlight hovered rows #231).

It also fixes older facts on the site that had gone stale.

README

• One paragraph on project groups, the tab menu and Alt+drag.
• The pane-menu caption mentions Move to tab….

docs/

• features.md: the tab-menu row, immediate saving of tab rename and colour, the sideways-wheel fix, and bindings.toml (was config.toml).
• keybindings.md: right-click a tab, the wheel over the tab bar, and Move to tab….
• configuration.md: a new project-groups.json section (location, shared by windows on one machine, a bad file moved to .bak).
• tmux-comparison.md: swap-pane and select-layout/spread are now covered by Alt+drag (mouse only) and Layout… / tab.layout_* (no default key). The summary is recounted per table row, with a definition line and a new "Reachable, no default key" bucket. The old figures followed no single rule.
• competitive-analysis.md: the Groups row goes from ❌ to 🟡 (v1.79), and gap feat: embed Windows exe icon + fix pane CWD not applied #20 is marked partly covered.
• roadmap.md: a "v1.76.0–v1.79.0" completed entry, and M17 item 16 marked partly shipped.

Site (site/src/data)

• features.ts:
  • New entry: "Rearrange tabs and panes, still running".
  • A groups bullet under projects, and a tab-bar wheel bullet under splits.
  • Stale facts corrected: the pane menu has 13 actions (not nine), the pin is a purple border with ◆ (not green), the registry holds 66 actions in bindings.toml (not 41 in config.toml), and the key presets have shipped.
• competitors.ts: Quil's "Session lifecycle mgmt" moves from no to partial, with a note. The tmux migration note names the tmux preset in bindings.toml. Competitor cells are unchanged.

Every number and claim was checked against the code: the pane-menu row count, the keymap registry count, the presets, the pin colour, the release-to-PR mapping, project-groups.json behaviour, and the scope of the competitor-matrix change.

Not included

• No new screenshots. The README's pane-menu image predates the Move to tab… row, and the groups, tab menu and new site entry have no image yet.
• docs/roadmap.md still says "as of v1.69.0", because v1.70–v1.75 have no entries yet.

Checks

• The site builds with the same steps as the CI site job: npm ci && npm run build in node:22, covering header stacking, trailing slashes, astro check and astro build. All 16 pages built.
• No changelog fragment: the release and changelog gates skip docs/, site/ and root *.md, so this PR cuts no release.

[codecov]

Welcome to Codecov 🎉

Once you merge this PR into your default branch, you're all set! Codecov will compare coverage reports and display results in all future pull requests.

Thanks for integrating Codecov - We've got you covered ☂️

[code-spire-beaver]

Reviewed 5f7c685 against base 9695229. No actionable findings in the nine changed documentation and site-data files.

Per-lens results:

• Security: clean. Changes are static prose/data rendered through Astro text interpolation; no new executable behavior, secrets, external-input handling, or dependencies. Optional Semgrep skipped because this diff only changes documentation and static content; GitHub CodeQL passed.
• Correctness: checked new feature claims against menu builders, keymap registry and tmux preset, wheel handling, move destination filtering, layout implementation, tab-save scheduling, project-group loading/quarantine, and release history. Confirmed 13 pane-menu actions, 66 registry entries, the six unbound layout actions, and the comparison summary totals (48 rows: 15 exact, 11 analogues, 6 reachable without default keys, 1 deliberately unbound, 15 absent). No new findings.
• Rules: applied .claude/CLAUDE.md and dev-environment.md; global no-synthetic-data, clean-code-general, clean-code-react, seo-react, observability-and-logging, documentation-maintenance, and blog-material-capture, where relevant to static content. Commit messages and documentation scope checked. Configured review-memory paths and matching prior review state were absent. No violations found.
• QA: in an isolated archive, node:22 npm ci && npm run build passed. Header stacking and trailing-slash checks passed; astro check inspected 37 files with 0 errors, 0 warnings, and 0 hints; astro build generated 16 pages. Verified the new feature anchor occurs once in generated HTML and updated feature prose is present. git diff --check passed. All GitHub checks passed. No Go tests rerun locally because no runtime Go changes are present.

Residual scope: no manual browser or terminal interaction; unchanged competitor claims were not re-audited. The working repository was left unchanged.

Findings: none. Reviewed head 5f7c685b31 as @code-spire-beaver.

[code-spire-beaver]

✅ APPROVED

Approved at 5f7c685. No actionable findings after reviewing documentation accuracy, security, project rules, and site validation. The changed claims match the implementation and release history; the comparison totals reconcile. The isolated Node 22 site build passed (37 files checked without diagnostics, 16 pages built), and all GitHub checks passed.

Agent findings: 0 resolved, 0 open. CI: 9/9 checks passing. Head 5f7c685b31, reviewed by @code-spire-beaver.