docs(releases): align alpha.5 notes and template with main

[wstein]

Brings the v0.1.0-alpha.5 notes and TEMPLATE.md in line with main: checksum block first, then the optional gh attestation verify block (skipped on a first install), then unpack and sudo ./install.sh; the sentence about the tag/archive binding (#524) corrected; next steps as the administrator (/opt/whr/bin/whr setup, which now also initializes the workharbor account, #529; whr setup host stays an alias) and as workharbor in its desktop session; highlights for #268, #495, #525 and #529; Known limits now also name the account initialization with sudo -u, the administrator's view into /Users/workharbor and the root:wheel archive entries as unverified.

Opus review: CLEAR at 89ade146 (install blocks pass zsh -n and bash -n, claims checked against install-release.sh, goreleaser.yaml and the manual, every listed PR and issue verified with gh, go test ./scripts exit 0), three wording Lows fixed, CLEAR at 3cc0f61; rebased onto ca16ad8 with an identical range-diff (3a3fa83). Open Low: the cd-back instruction cannot find the mktemp directory (logged on #399).

Refs: #443

🤖 Generated with Claude Code

[wstein]

Opus review CLEAR at 3cc0f61 (full review at 89ade146, three wording Lows fixed, install blocks pass zsh -n and bash -n, every listed PR and issue verified, go test ./scripts exit 0); this head 3a3fa83 is the same commit rebased onto ca16ad8 with an identical range-diff.

Co-Authored-By: Claude Sonnet 5.5 [email protected]