docs: refresh README for the v0.1.0-alpha release

[saadqbal]

Summary

Closes #23.

v0.1.0-alpha is published (pre-release), so the README's "first release pending" framing is stale. While refreshing it I found the advertised install path is non-functional for the alpha, so this fixes that too rather than just swapping wording:

• install.tracebloc.io doesn't resolve — the vanity domain isn't wired up.
• GitHub's releases/latest skips pre-releases, so a latest-based one-liner can't find the alpha either.

Changes (docs only)

• Status §: first release pending / no tagged release exists yet → v0.1.0-alpha published (pre-release), with the signed-artifact set described.
• Customer experience §: replaced the dead curl https://install.tracebloc.io | sh / irm … commands with the working explicit-tag install —

  curl -fsSL https://github.com/tracebloc/cli/releases/download/v0.1.0-alpha/install.sh | sh -s -- --version v0.1.0-alpha
  

  plus a link to the release page for Windows/manual/signed downloads. Noted that the domain shortcut, latest one-liner, and Homebrew tap all await the first stable v* tag.
• Roadmap: Phase 5 awaiting first v* tag → v0.1.0-alpha published.

Note for reviewer

The framing "domain shortcut / latest / Homebrew await the first stable tag" is my assumption — if install.tracebloc.io is meant to be wired now, say so and I'll adjust. The unresolved domain may warrant its own infra ticket (flagged separately).

🤖 Generated with Claude Code

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Note

Low Risk
Documentation-only; no code, CI, or release pipeline behavior changes.

Overview
Updates README now that v0.1.0-alpha is out, replacing “first release pending” / “no tagged release” copy with links to the pre-release and a short description of cosign-signed artifacts, SHA256SUMS, and install scripts.

Customer experience no longer points at install.tracebloc.io or a latest-based one-liner (called out as broken for pre-releases). It documents explicit-tag install via the GitHub release install.sh and the release page for Windows/manual downloads, and notes that the vanity domain, latest shortcut, and Homebrew tap wait for the first stable v* tag.

The roadmap Phase 5 row is updated from “awaiting first v* tag” to published v0.1.0-alpha (pre-release).

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[LukasWodka]

👋 Heads-up — Code review queue is at 12 / 8

Above the WIP limit. The team convention is to review existing PRs before opening new work.

Open PRs currently in Code review (oldest first):

• averaging-service#98 — ci: add fr-gate caller workflow · author: @LukasWodka · no reviewer assigned
• cli#22 — Sync develop → main for v0.1.0-alpha · author: @aptracebloc · no reviewer assigned
• client#191 — fix(#190): fail image-refresh loudly when the ingestor (ghcr) digest can't resolve · author: @saadqbal · no reviewer assigned
• client-runtime#75 — dev to staging · author: @shujaatTracebloc · reviewer: @saadqbal
• data-ingestors#146 — test(schema): lock category enum to the engine's TaskCategory (anti-drift) · author: @LukasWodka · reviewer: @saadqbal
• design-system#19 — fix: un-track coverage/ and node_modules/ from git · author: @LukasWodka · no reviewer assigned
• design-system#22 — ci: add Vitest test workflow · author: @LukasWodka · reviewer: @aptracebloc
• design-system#23 — ci: add fr-gate caller workflow · author: @LukasWodka · no reviewer assigned
• docs#46 — docs: make declarative-ingest staging self-contained (data-ingestors#131 B/C) · author: @divyasinghds · no reviewer assigned
• frontend-app#499 — ci: add Vitest + Cypress test workflow · author: @LukasWodka · reviewer: @aptracebloc

Pull from review before opening new work. (This is a nudge from the kanban WIP check, not a block.)