Plugin version check fails on dev builds with v-prefix (git describe output)

[pocky]

Description

Plugins fail to start on development builds (main branch or in-progress work) because the version compatibility check rejects versions produced by git describe --tags --always --dirty.

Error

some plugins failed to start error=init plugin event-logger: init [event-logger]: version compatibility check failed: version: invalid format "v0.8.1-dirty"
init plugin awf-plugin-time: init [awf-plugin-time]: version compatibility check failed: version: invalid format "v0.8.1-dirty"

Root Cause

The Makefile sets Version via git describe --tags --always --dirty, which produces strings like:

Git state	Output
At tag, clean	v0.8.1
At tag, dirty	v0.8.1-dirty
Commits after tag	v0.8.1-3-gabcdef
Commits after tag, dirty	v0.8.1-3-gabcdef-dirty

ParseVersion() in pkg/registry/version.go does not strip the leading v prefix before applying the semver regex, causing all git describe outputs to fail parsing. The NormalizeTag() helper exists for this purpose but is never called in the version check flow.

Additionally, effectiveCLIVersion() only handles the "dev" prefix case and passes non-parseable git describe output (e.g., v0.8.1-3-gabcdef-dirty) through unchanged, which also fails parsing.

Fix

1. ParseVersion() — Strip leading v prefix before regex matching. All callers (plugins, packs, constraints) benefit automatically.
2. effectiveCLIVersion() — Fall back to "999.0.0" when the version string is not valid semver (handles complex git describe output with commit count and hash).

Affected Versions

Any development build from v0.8.0+ (when plugin system was introduced).

[pocky]

Closed by #344