fix: use generic dev version fallback

[joshavant]

Summary

This changes the built-in fallback version from a stale release-like value (0.13.0-dev) to a neutral dev value.

Release builds already inject the real version, commit, and date through GoReleaser ldflags, so this does not change the published release artifact behavior. It only affects binaries built without those linker flags, such as plain go build or go install github.com/steipete/gogcli/cmd/gog@<version>.

Why

The hardcoded fallback can drift after releases. When it does, source-installed binaries from a newer tag can report an older dev version, which makes support diagnostics and packaging verification misleading.

For example, a binary built from a tagged module version should not look like a stale 0.13.0-dev build simply because it was not built through GoReleaser.

Why This Change

Using dev is the lowest-blast-radius fix:

• It preserves the existing GoReleaser workflow and release metadata injection.
• It avoids requiring release automation changes.
• It avoids a future maintenance burden of updating a hardcoded fallback every release.
• It makes non-release builds clearly identify as unversioned development/source builds instead of masquerading as a stale pre-release.

A more complete future improvement could infer the module version from runtime/debug.ReadBuildInfo() for go install module@version, but this one-line change fixes the misleading output without changing release behavior.

Verification

• go test ./internal/cmd
• go test ./cmd/gog
• go build -o /tmp/gog-dev ./cmd/gog && /tmp/gog-dev --version prints dev
• go build -ldflags \"-X github.com/steipete/gogcli/internal/cmd.version=v9.9.9 -X github.com/steipete/gogcli/internal/cmd.commit=abc123 -X github.com/steipete/gogcli/internal/cmd.date=2026-05-01T00:00:00Z\" -o /tmp/gog-release ./cmd/gog && /tmp/gog-release --version prints v9.9.9 (abc123 2026-05-01T00:00:00Z)

[joshavant]

Closing this in favor of a replacement PR that preserves the low-blast-radius fallback behavior while also using Go build metadata to report the installed module version for .