Add development-scripts agent skill

Ports generic-scripts-module-v1 into a routed skill: module anatomy, shared
loggers/base modules, Taskfile integration, workflows, and pattern decisions.

Fixes a latent defect in the loggers example that silenced all logging in the
module scaffold: loggers/lib/--index-api.sh now sources --env-vars-reader.sh,
and the reader preserves already-exported values so caller overrides still win.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

references/module-patterns.md

@@ -0,0 +1,66 @@
+# Module Patterns
+
+A decision guide for what kind of module you are building and how it should connect to the
+others.
+
+---
+
+## 1. Module type
+
+| Module type | Has `api/` | Has `Taskfile.yml` | Example |
+|---|:---:|:---:|---|
+| Support-only library | No | No | `loggers` |
+| Shared foundation with public commands | Yes | Optional / no | `base` |
+| Feature module | Yes | Usually yes | `kube`, `github`, `data-migration` |
+| Wrapper around an external CLI | Yes | Usually yes | `helm`, `openshift`, `github` |
+
+Pick the type before creating any file — it decides whether `api/` and `Taskfile.yml` exist at
+all, and adding them later means reworking every consumer that has already started sourcing
+the module.
+
+A module with no user-facing command is a support library. Do not give it an `api/` directory
+speculatively; every file in `api/` is a public interface someone may come to depend on.
+
+---
+
+## 2. Dependency sourcing
+
+| You need | Source |
+|---|---|
+| Logging | `./.scripts/loggers/lib/--index-api.sh` |
+| Shared base functions | `./.scripts/base/lib/--index-api.sh` |
+| Another module's exported functions | that module's `lib/--index-api.sh` |
+| Your own module's full runtime, from its `api/` wrapper | your `lib/--index.sh` |
+
+The rule underneath: **`--index-api.sh` is the public edge between modules; `--index.sh` is a
+module's own private entrypoint.** Sourcing another module's `--index.sh` runs its reader and
+validator inside your command — importing its defaults, its required-input checks, and in
+`base`'s case its `.env` loading. Symptoms show up as variables nobody set, or a validation
+failure naming a module the user never invoked.
+
+---
+
+## 3. Command exposure
+
+Three independent decisions, in increasing order of commitment:
+
+1. **`lib/` only** — internal. Reachable from other modules that source your `--index-api.sh`.
+2. **`api/<command>.sh`** — user-facing. Someone can run it directly from the repository root.
+3. **Module `Taskfile.yml`** — discoverable through `task --list-all`.
+4. **Root `Taskfile.yml` include** — a stable public namespace, effectively permanent.
+
+Escalate only as far as the command genuinely needs. Each step is easy to add later and
+disruptive to withdraw, because each one is a promise someone may already be relying on.
+
+---
+
+## 4. Common mistakes
+
+- Putting full implementation logic into `api/*.sh`.
+- Adding a `lib/-*.sh` file and forgetting to source it from `lib/--index-api.sh`.
+- Parsing CLI flags in implementation files instead of `--env-vars-reader.sh`.
+- Printing secrets in logs.
+- Sourcing `base/lib/--index.sh` from a library function and unexpectedly loading `.env`.
+- Adding root Taskfile includes for experimental modules.
+- Giving a support-only library an `api/` directory it does not need.
+- Mixing function prefixes inside one module after a rename.