docs: working install URLs, a book sweep, and an English sidebar label

[guillaumejay]

Why

Installing on Linux with the documented one-liner failed:

curl … https://github.com/Termherd/termherd/releases/latest/download/termherd-installer.sh
curl: (22) The requested URL returned error: 404

Two independent causes, either one enough:

• every release so far is a pre-release, and /releases/latest/ skips
  pre-releases, so it resolves to nothing;
• dist names the installers after the package: termherd-app-installer.sh /
  .ps1, not termherd-installer.*.

What

Install (README.md, docs/src/guide/installation.md): the one-liners
name the tag and the real file. All three documented URLs checked at 200. The
attestation example used the wrong tarball name too, and the SHA256SUMS it
promised comes from a signing workflow added after v0.1.0-prerelease.4, so
no published release has it yet — the page now says so and points at the
.sha256 / sha256.sum files that do exist.

Book sweep against the source:

• README live-bridge table lacked prompt_in_session, and still listed it as
  a pending follow-up (F-mcp-agent-loop: composed prompt->wait->read over any session (shell or Claude) #196 shipped it).
• mcp.allow_claude_nesting was missing from the settings reference, the
  template, the README list, the file-only enumerations and the complete
  example.
• mcp/keyboard.md: the step field is result, not outcome; the close
  prompt reports as tab-close-confirm; the second rename ignoring enter is
  tab-rename.
• termherd://keys/schema omits activate-tab-N and shows no default for
  copy / paste; three pages claimed the whole catalogue.
• snapshot's focused_terminal argument was undocumented.
• quick-start claimed keyboard resize of splits; nothing resizes them.
• tabs-and-splits gave Shift+→ for Cmd/Ctrl+Shift+→.
• chord syntax now lists the modifier aliases and plus.
• create-missing = false checks SUMMARY.md only, not in-page links.
• the copy chord asks the terminal for its selection (even scrolled out of
  view) rather than reading the screen.
• AGENTS.md counted sixteen live-bridge tools; there are seventeen.

Code: the sidebar's collapse button was hard-coded in French
("◀ Masquer le panneau") outside strings.rs; it now reads
strings::SIDEBAR_HIDE = "◀ Hide", as the book shows.

Chore: .serena/ (Serena MCP tool state) is gitignored.

Checks

• markdownlint-cli2: 0 issues
• cargo fmt --all --check, cargo clippy -p termherd-app --all-targets -- -D warnings: clean
• cargo test -p termherd-app: green
• mdbook build not run locally (not installed) — left to the book job

🤖 Generated with Claude Code