STAT-115-remove-check-shared-block: Remove claude/check-shared-block composite action

Superseded by a live @../stat-tackler-claude/CLAUDE.md import, which
means there is no per-repo copy left to drift and nothing left to check
(part of STAT-115).

Claude-Session: https://claude.ai/code/session_01FS9R1ZEc8Vu7hg2PmzqbpP

Makefile

@@ -1,7 +1,6 @@
 ACTIONS := \
 	docker \
 	node \
-	claude/check-shared-block \
 	git/create_tag \
 	git/promotion-gate \
 	helm/diff \

README.md

@@ -4,12 +4,6 @@ Reusable composite actions for Gitea CI/CD pipelines.
 
 ## Actions
 
-### Claude
-
-| Action | Description |
-|---|---|
-| [claude/check-shared-block](claude/check-shared-block/README.md) | Fails when a repo's shared CLAUDE.md block has drifted from the canonical copy in stat-tackler-infra |
-
 ### Docker
 
 | Action | Description |

claude/check-shared-block/README.md

@@ -1,44 +0,0 @@
-# Check Shared CLAUDE.md Block
-
-<!-- action-docs-description source="action.yml" -->
-## Description
-
-Fails when a repo's shared CLAUDE.md block has drifted from the canonical copy in stat-tackler-infra
-<!-- action-docs-description source="action.yml" -->
-
-<!-- action-docs-inputs source="action.yml" -->
-## Inputs
-
-| name | description | required | default |
-| --- | --- | --- | --- |
-| `TARGET` | <p>Path to the CLAUDE.md file to check</p> | `false` | `CLAUDE.md` |
-| `CANONICAL_URL` | <p>Raw URL of the canonical shared fragment</p> | `false` | `https://gitea.pixelparasol.com/stat-tackler/stat-tackler-infra/raw/branch/main/docs/CLAUDE.shared.md` |
-| `GITEA_TOKEN` | <p>Gitea token with read access to stat-tackler-infra, if it is private</p> | `false` | `""` |
-<!-- action-docs-inputs source="action.yml" -->
-
-<!-- action-docs-runs source="action.yml" -->
-## Runs
-
-This action is a `composite` action.
-<!-- action-docs-runs source="action.yml" -->
-
-## Running locally
-
-The check logic has no dependency on the composite action wrapper beyond
-`curl`, `awk`, and `diff` on `PATH`. From a repo's root:
-
-```bash
-CANONICAL_URL=https://gitea.pixelparasol.com/stat-tackler/stat-tackler-infra/raw/branch/main/docs/CLAUDE.shared.md \
-  TARGET=CLAUDE.md sh -c '
-    extract() { awk "/<!-- SHARED:BEGIN/{f=1} f{print} /SHARED:END -->/{f=0}" "$1"; }
-    tmp=$(mktemp)
-    curl -sfSL "$CANONICAL_URL" -o "$tmp"
-    extract "$tmp" > "$tmp.canon"
-    extract "$TARGET" > "$tmp.mine"
-    diff -u "$tmp.canon" "$tmp.mine" && echo "matches canonical"
-    rm -f "$tmp" "$tmp.canon" "$tmp.mine"
-  '
-```
-
-`GITEA_TOKEN` is only needed if `stat-tackler-infra` becomes private; it is
-otherwise safe to omit.

claude/check-shared-block/action.yml

@@ -1,75 +0,0 @@
-name: Check Shared CLAUDE.md Block
-description: Fails when a repo's shared CLAUDE.md block has drifted from the canonical copy in stat-tackler-infra
-
-inputs:
-  TARGET:
-    description: "Path to the CLAUDE.md file to check"
-    default: "CLAUDE.md"
-  CANONICAL_URL:
-    description: "Raw URL of the canonical shared fragment"
-    default: "https://gitea.pixelparasol.com/stat-tackler/stat-tackler-infra/raw/branch/main/docs/CLAUDE.shared.md"
-  GITEA_TOKEN:
-    description: "Gitea token with read access to stat-tackler-infra, if it is private"
-    default: ""
-
-runs:
-  using: composite
-  steps:
-    - name: Checkout
-      uses: actions/checkout@v4
-
-    - name: Check shared CLAUDE.md block
-      shell: sh
-      env:
-        TARGET: ${{ inputs.TARGET }}
-        CANONICAL_URL: ${{ inputs.CANONICAL_URL }}
-        GITEA_TOKEN: ${{ inputs.GITEA_TOKEN }}
-      run: |
-        set -e
-
-        if [ ! -f "$TARGET" ]; then
-          echo "::error::$TARGET not found"
-          exit 1
-        fi
-
-        extract() {
-          # Everything between the markers, markers included.
-          awk '/<!-- SHARED:BEGIN/{f=1} f{print} /SHARED:END -->/{f=0}' "$1"
-        }
-
-        mine=$(extract "$TARGET")
-        if [ -z "$mine" ]; then
-          echo "::error::$TARGET has no SHARED:BEGIN/SHARED:END block."
-          echo "Copy it from $CANONICAL_URL"
-          exit 1
-        fi
-
-        tmp=$(mktemp)
-        if [ -n "$GITEA_TOKEN" ]; then
-          curl -sfSL -H "Authorization: token $GITEA_TOKEN" "$CANONICAL_URL" -o "$tmp"
-        else
-          curl -sfSL "$CANONICAL_URL" -o "$tmp"
-        fi
-
-        theirs=$(extract "$tmp")
-        if [ -z "$theirs" ]; then
-          echo "::error::Could not read the canonical block from $CANONICAL_URL"
-          exit 1
-        fi
-
-        if [ "$mine" = "$theirs" ]; then
-          echo "Shared CLAUDE.md block matches the canonical copy."
-          rm -f "$tmp"
-          exit 0
-        fi
-
-        echo "::error::The shared CLAUDE.md block has drifted from the canonical copy."
-        echo "Canonical: $CANONICAL_URL"
-        echo
-        echo "--- canonical"
-        echo "+++ $TARGET"
-        printf '%s\n' "$theirs" > "$tmp.canon"
-        printf '%s\n' "$mine" > "$tmp.mine"
-        diff -u "$tmp.canon" "$tmp.mine" || true
-        rm -f "$tmp" "$tmp.canon" "$tmp.mine"
-        exit 1