Remove duplicate issue detection workflow (#1865)

Removes the issue-opened duplicate detection workflow entirely. It is
not part of product CI and currently depends on separately funded
Anthropic API credits. No replacement, fallback, or failure-suppression
path is added.\n\nValidation: `git diff --check`; `uv run prek run
--all-files`.

.github/workflows/duplicate-issue-detection.yml

@@ -1,96 +0,0 @@
-name: Duplicate Issue Detection
-
-on:
-  issues:
-    types: [opened]
-
-jobs:
-  check-duplicates:
-    runs-on: ubuntu-24.04
-    permissions:
-      contents: read
-      issues: write
-    steps:
-      - name: Checkout repository
-        uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4
-        with:
-          fetch-depth: 1
-
-      - name: Set up Python
-        uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5
-        with:
-          python-version: "3.13"
-
-      - name: Install uv
-        uses: astral-sh/setup-uv@d0cc045d04ccac9d8b7881df0226f9e82c39688e # v6
-        with:
-          version: "0.11.3"
-          enable-cache: false
-
-      - name: Resolve OpenCode and workflow tools through abxpkg
-        env:
-          ABXPKG_LIB_DIR: ${{ runner.temp }}/abx-lib
-        run: |
-          set -Eeuo pipefail
-          uv sync --no-cache --locked --no-sources --no-install-project
-          OPENCODE_CONFIG="$(uv run --no-cache --no-sync --no-sources python -c 'from abx_plugins import get_plugins_dir; print(get_plugins_dir() / "opencode" / "config.json")')"
-          mkdir -p "$ABXPKG_LIB_DIR/env/bin"
-          export PATH="$ABXPKG_LIB_DIR/env/bin:$PATH"
-          echo "ABXPKG_LIB_DIR=$ABXPKG_LIB_DIR" >> "$GITHUB_ENV"
-          echo "$ABXPKG_LIB_DIR/env/bin" >> "$GITHUB_PATH"
-          opencode_env="$(
-            uv run --no-cache --no-sync --no-sources abxpkg env \
-              --install \
-              --json \
-              --lib="$ABXPKG_LIB_DIR" \
-              --deps-from="$GITHUB_WORKSPACE/.github/configs/ci-tooling.json:ci_binaries" \
-              --deps-from="$GITHUB_WORKSPACE/.github/configs/ci-tooling.json:github_binaries" \
-              --deps-from="$OPENCODE_CONFIG:required_binaries"
-          )"
-          jq_binary="$ABXPKG_LIB_DIR/env/bin/jq"
-          "$jq_binary" -r 'to_entries[] | "\(.key)=\(.value)"' \
-            <<< "$opencode_env" >> "$GITHUB_ENV"
-
-          opencode_binary="$ABXPKG_LIB_DIR/env/bin/opencode"
-          echo "OPENCODE_BINARY=$opencode_binary" >> "$GITHUB_ENV"
-          test -L "$opencode_binary"
-          test -x "$opencode_binary"
-
-      - name: Check for duplicate issues
-        env:
-          ANTHROPIC_API_KEY: ${{ secrets.ANTHROPIC_API_KEY }}
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-          OPENCODE_PERMISSION: |
-            {
-              "bash": {
-                "gh issue*": "allow",
-                "gh pr*": "allow",
-                "*": "deny"
-              },
-              "webfetch": "allow"
-            }
-        run: |
-          "$OPENCODE_BINARY" run -m anthropic/claude-haiku-4-5 "A new issue has been created:
-
-          Issue number:
-          ${{ github.event.issue.number }}
-
-          Lookup this issue and search through existing issues and PRs (excluding #${{ github.event.issue.number }}) in this repository to find any potential duplicates of this new issue.
-          Consider:
-          1. Similar titles or descriptions
-          2. Same error messages or symptoms
-          3. Related functionality or components
-          4. Similar feature requests
-
-          If you find any potential duplicates, please comment on the new issue with:
-          - A brief explanation of why it might be a duplicate
-          - Links to the potentially duplicate issues or PRs
-          - A suggestion to check those issues first
-
-          Use this format for the comment:
-          'This issue might be a duplicate of existing issues. Please check:
-          - #[issue_number]: [brief description of similarity]
-
-          Feel free to ignore if none of these address your specific case.'
-
-          If no clear duplicates are found, do not comment."