Install the tracebloc CLI as part of the client installer (macOS/Linux + Windows)

[saadqbal]

Context

When a user installs the client via scripts/install.sh (macOS/Linux) or scripts/install.ps1 (Windows), also install the tracebloc CLI (tracebloc/cli) so they can tracebloc dataset push ./data against the client they just set up — no separate install step.

Approach

• New scripts/lib/install-cli.sh with install_tracebloc_cli() that reuses the CLI's own released, signed installer (curl -fsSL https://github.com/tracebloc/cli/releases/latest/download/install.sh | sh) — inherits SHA256 + cosign verification and 8-arch detection, no duplication.
• Non-fatal: a CLI-install failure must never break the ✔ Connected to tracebloc success (set -e is on) — warn + 'install later' hint, never error.
• New Step 5/5 after wait_for_client_ready; renumber step N 4→N 5 + print_roadmap.
• Wire install-cli.sh into the bootstrap FILES=() in install.sh.
• Windows parity: equivalent Install-TraceblocCli in install-k8s.ps1 (via the CLI's install.ps1), Step 5/5.
• Summary: add tracebloc dataset push ./data to 'What to do next'.
• Docs: docs/INSTALL.md. Tests: bash -n/shellcheck + a bats non-fatal case; PS parse check.

Acceptance criteria

• Installing the client (bash + PowerShell) installs tracebloc and a fresh shell resolves it.
• CLI-install failure leaves the client install succeeding (non-fatal).
• Targets develop.

[saadqbal]

Shipped via #202 (merged to develop): CLI installs as Step 5 in both installers; guards + Lint/Unit-tests CI added.