Add vctl and vctx Vault token CLIs

Introduces the vault-tools monorepo: two Go CLIs that share a config file
(~/.config/vault) and token cache (~/.cache/vault) for working with multiple
Vault instances (contexts).

- add shared/ library: config parsing (vctl.yaml/config.yaml, per-context
  overrides, slash contexts), token cache (0600/0700, atomic writes, path-
  traversal guards), and a small hand-rolled Vault HTTP client (login/renew)
- add vctl: login/renew (single or --all), list, --method/--user overrides,
  no-echo password/token prompts, dynamic context completion
- add vctx: resolve a context, set VAULT_ADDR/VAULT_TOKEN/VAULT_NAMESPACE and
  exec the vault CLI, passing remaining args through untouched
- add unit tests across shared/, vctl and vctx command layers (config
  resolution, cache paths, vault client, --all iteration + error aggregation,
  vctx arg pass-through and env construction via fakeable exec/prompt seams)
- add Makefile (build/test/completions/rpm, patch|minor|major version bumps),
  nfpm RPM packaging bundling bash/zsh/fish completions for both binaries
- add Woodpecker pipelines: build/test/pre-commit on PRs, and a tag release
  that cross-compiles, builds+uploads the RPM to artifactapi, and cuts a Gitea
  release (serviceAccountName default, k8s resources on every step)
- add README, per-command docs (docs/vctl.md, docs/vctx.md), AGENTS.md and an
  example config

Claude-Session: https://claude.ai/code/session_015ur3i7D2azsMAWTSVABApv

.woodpecker/pre-commit.yaml

@@ -0,0 +1,18 @@
+when:
+  - event: pull_request
+
+steps:
+  - name: pre-commit
+    image: git.unkin.net/unkin/almalinux9-gobuilder:20260606
+    commands:
+      - uvx pre-commit run --all-files
+    backend_options:
+      kubernetes:
+        serviceAccountName: default
+        resources:
+          requests:
+            memory: 512Mi
+            cpu: 1
+          limits:
+            memory: 2Gi
+            cpu: 2