Update Methodology Library

The Guardian Methodology Library currently contains 90+ policy folders containing .policy bundles, README files, and assorted supporting documents. None of this content is machine-readable in a structured way. Discovering, filtering, and comparing policies requires manually reading Markdown files or relying on institutional knowledge. Furthermore, policies such as ACM0002 and others are being [deprecated](https://verra.org/methodologies/vmr0017-grid-connected-electricity-generation-from-renewable-sources-acm0002-revision-v1-0/) by registries and receiving new updates.

Assess how to improve the library and pave the way for building new ways to interact with the library, be sensitive to existing policy files, stakeholders, and dependencies, and more.

**Goals**

* Establish a single, validated, machine-readable metadata contract for every policy in the library
* Enable ability to perform filtering, search, and catalog rendering without special parsing
* Include a way to track policy lineage (supersession / depregation), publication history (multi-network), and registry validation status
* Provide a contributor-facing spec that is lightweight enough that a new contributor can fill out a manifest in under 30 minutes.
* Enforce minimum metadata via JSON Schema validation in CI
* Create foundations for a library mini-site and Guardian platform integration in the future

### **Non-Goals**

* Replacing the README. existing documentation can be left as is and will remain the responsibility of the author. We will not take on the task of updating README or supporting assets for all policies
* Enforcing a closed metadata tag set. Tags are guidance-driven, not a hard closed enum
* Automating policy import/export into Guardian. This is a metadata layer, not a deployment mechanism.
* Defining or enforcing the schema of the `.policy` file itself. The manifest describes the policy; it does not replace the policy bundle format.
* Providing a UI in this phase. Provide the infrastructure so that a sensible catalog UI, among other features will be possible from these foundations

# Acceptance Criteria

* [x] plan to apply policy metadata across methodology library
* [x] agreed upon repo updates, signed off by Jailine & Wes
* [ ] minimum quality requirements applied across all methodologies
* [ ] standard template applied across all methodologies
* [ ] updated contributor guidelines
* [ ] policies that don't meet quality requirements de-emphasized

# Artifacts / Resources

* [See RFC, Policy.yaml manifest](https://docs.google.com/document/d/1O32A33eMQ6EMHMIubZceR9XFFSv_dnOXTRYIUTb_Q-A/edit?tab=t.0)
* [Library Cleanup Workshop](https://app.mural.co/t/exploros/m/exploros/1778777285791/e74fad28bbac8ed66d5475c9417f60cf8171008b?sender=ub8e26b0f98a64f89f0be1082)
* [See Helm.yaml for a similar format](https://helm.sh/docs/topics/charts/)