Document Windows package-manager installation and release maintenance

## Outcome

After WinGet, Scoop, and Chocolatey have public, tested identifiers and finalized update mechanics, publish one authoritative user installation section and one recurring maintainer procedure using the exact accepted identifiers, URLs, commands, workflows, and credential names.

## Scope

- `README.md`
- WinGet, Scoop, and Chocolatey installation, update, and uninstall commands.
- WinGet 1.5+ requirement where applicable.
- Scoop Extras bucket prerequisite.
- Public catalog and package links.
- Common post-install verification.
- `.opencode/agent/new-release.md`
- Correct current source paths, including the stale `internal/cmd/root.go` reference.
- Require successful Release and Windows smoke workflows.
- Record each manager's actual update and submission procedure.
- Record moderation, approval, and catalog-availability checks.
- Record credential boundaries.
- `CHANGELOG.md`
- One concise #57 entry under `[Unreleased]`.
- No version bump.

Do not use provisional identifiers or duplicate package-manager definitions.

## Acceptance criteria

AC1. `README.md` contains each manager's accepted identifier, public package or catalog link, prerequisites, and copy-paste installation, update, and uninstall commands with no placeholders.

AC2. The README's verification block uses `Get-Command logbasset`, `logbasset --version`, and `logbasset --help`, and those commands pass after each documented installation path on clean Windows amd64.

AC3. README accurately states Windows amd64 or x64, the version-specific portable ZIP and SHA256 basis, Apache-2.0 metadata, and unsigned status without promising SmartScreen or Mark-of-the-Web suppression.

AC4. `.opencode/agent/new-release.md` uses `internal/app/app.go` as the current fallback-version source and orders release publication, successful Windows smoke, each manager's update step, external moderation or acceptance, catalog-version confirmation, and clean-Windows checks.

AC5. The runbook names only the accepted workflow, secret, and account names, explains where each credential is needed, and contains no secret value or instruction to place a token in source or logs.

AC6. `CHANGELOG.md` contains one concise #57 entry under `[Unreleased]` covering all three managers and no unrelated changelog changes.

AC7. The implementation diff is limited to the three named shared documentation files and does not modify package definitions, scripts, update workflows, or artifact verification.

## Verification

Compare every identifier, URL, command, workflow, and credential name with the completed package-child evidence.

On clean Windows amd64, execute each documented install, verify, update, and uninstall sequence verbatim. Confirm the installed version matches the catalog version and uninstall removes the command.

## Exclusions

Package definitions and submissions, update automation changes, workflow or GoReleaser changes, signing, Microsoft Store, Windows ARM64, version bump, new CLI behavior, and unverified SmartScreen or Mark-of-the-Web claims.

## Credentials

No new credential. Public documentation may name established secret or account names but must never contain their values.

Parent: #57
Blocked by: #59, #60, #61

Start by reading the package-child evidence for #59, #60, and #61, since this issue is blocked on their accepted identifiers and update mechanics. Review README.md, .opencode/agent/new-release.md, and CHANGELOG.md against that evidence, including the named source path, workflows, and credential names. On clean Windows amd64, run each documented installation, verification, update, and uninstall sequence; done means all acceptance criteria pass with changes limited to those three files.

Written by the indexing model from the issue text.