ci: switch versioning from CalVer to SemVer

Go module tooling requires v-prefixed semver tags (go install @latest
ignores CalVer tags entirely), GoReleaser errors on non-semver tags,
and zero-padded CalVer months are invalid semver. Old CalVer tags and
releases were deleted due to pre-release security issues; relaunch
tags as v1.0.0.

- Workflow tag triggers: [0-9]* -> v[0-9]* (Gitea + GitHub relay)
- cliff.toml tag_pattern: regex v[0-9].* (was matching everything --
  tag_pattern is regex since git-cliff 1.4, not glob)
- Docker image tags drop the v prefix per registry convention

.gitea/workflows/release-binaries.yml

@@ -3,7 +3,7 @@ name: Release Binaries
 on:
   push:
     tags:
-      - "[0-9]*"
+      - "v[0-9]*"
 
 jobs:
   release:

.gitea/workflows/release-docker.yml

@@ -3,11 +3,11 @@ name: Release Docker
 on:
   push:
     tags:
-      - "[0-9]*"
+      - "v[0-9]*"
   workflow_dispatch:
     inputs:
       tag:
-        description: "Image tag (e.g. 2026.06.1). Defaults to latest commit SHA."
+        description: "Image tag (e.g. 1.0.0, no v prefix). Defaults to latest commit SHA."
         required: false
 
 jobs:
@@ -27,7 +27,9 @@ jobs:
               TAG="${{ github.sha }}"
             fi
           else
+            # Docker convention: git tag v1.2.3 -> image tag 1.2.3
             TAG="${{ github.ref_name }}"
+            TAG="${TAG#v}"
           fi
           echo "tag=$TAG" >> "$GITHUB_OUTPUT"
 

.github/workflows/mirror-release.yml

@@ -3,7 +3,7 @@ name: Mirror Release to GitHub
 on:
   push:
     tags:
-      - "[0-9]*"
+      - "v[0-9]*"
 
 permissions:
   contents: write

cliff.toml

@@ -23,7 +23,7 @@ filter_unconventional = true
 split_commits = false
 protect_breaking_commits = false
 filter_commits = false
-tag_pattern = "[0-9]*"
+tag_pattern = "v[0-9].*"
 topo_order = false
 sort_commits = "oldest"