chore: add pre-commit config and update CI pipeline

- .pre-commit-config.yaml with standard Go hooks: gofmt, go vet,
  go mod tidy, plus trailing whitespace, end-of-file, yaml check,
  large file check, merge conflict check
- go vet runs as a local hook with ./... to work correctly with
  Go modules (the dnephin hook runs per-file which breaks)
- Woodpecker pre-commit pipeline updated to use almalinux9-gobuilder
  image with uvx pre-commit run --all-files
- Pre-commit hooks installed into the repo

.pre-commit-config.yaml

@@ -0,0 +1,24 @@
+repos:
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v5.0.0
+    hooks:
+      - id: trailing-whitespace
+      - id: end-of-file-fixer
+      - id: check-yaml
+      - id: check-added-large-files
+      - id: check-merge-conflict
+
+  - repo: https://github.com/dnephin/pre-commit-golang
+    rev: v0.5.1
+    hooks:
+      - id: go-fmt
+      - id: go-mod-tidy
+
+  - repo: local
+    hooks:
+      - id: go-vet
+        name: go vet
+        entry: go vet ./...
+        language: system
+        types: [go]
+        pass_filenames: false