chore(rsr): declare capability profile (rsr-profile.a2ml, preset rust-cli) (#11)

## Summary

The **worked example** for the estate template-applicability policy
(companion to `hyperpolymath/standards#391`). Adds
`.machine_readable/rsr-profile.a2ml` declaring arghda-core's
capabilities — `preset = rust-cli` (rust, cli, library) — with a
`[rationale]` block recording why it declines the maximal template's
gated modules:

- **no `abi`/`ffi`** — language-agnostic engine, no C-ABI seam / Idris2
ABI proofs;
- **no `formal-proofs`** — it *consumes* Agda (shells out to
`agda`/`agda-unused`) but contains **no in-tree proofs**;
- **no
`container`/`reproducible-build`/`affinescript`/`governance-tier`**.

This turns arghda-core's already-lean shape from a judgement call into a
rule: the reference checker (`standards/scripts/check-rsr-profile.sh`)
reports **OK** against this profile, and flags a planted `abi.ipkg` /
`container/` as **VESTIGIAL**.

## Verification
- `bash scripts/check-spdx.sh` ✓ (new `.a2ml` carries `MPL-2.0`).
- `check-rsr-profile.sh /path/to/arghda-core` → OK (effective caps:
rust, cli, library).
- `STATE.a2ml` updated to point at `standards#391`; wiring the profile
check into arghda CI is a follow-up once that policy lands.

Depends on: hyperpolymath/standards#391 (defines the preset + gate model
this profile references).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

https://claude.ai/code/session_019GiSiEfgZCte35dyykgBHs

---
_Generated by [Claude
Code](https://claude.ai/code/session_019GiSiEfgZCte35dyykgBHs)_

Author: hyperpolymath

.machine_readable/6a2/STATE.a2ml

@@ -40,7 +40,7 @@ milestones = [
 
 [critical-next-actions]
 actions = [
-  "Formalise template-applicability rules (capability-gated RSR profile: carry a template module iff the repo declares the capability it serves) — estate-wide, candidate for hyperpolymath/standards",
+  "Template-applicability: rsr-profile.a2ml declares preset rust-cli (landed); estate policy + gate model + reference checker filed in hyperpolymath/standards#391. Follow-up: wire scripts/check-rsr-profile.sh into CI once standards#391 lands.",
   "Extend content-hash invalidation to cover transitive imports (needs include-root tracking)",
   "Serve /.well-known/groove for PanLL discovery (Groove protocol)",
   "Scaffold arghda-studio (AffineScript visual layer consuming the dag JSON)",

.machine_readable/rsr-profile.a2ml

@@ -0,0 +1,24 @@
+# SPDX-License-Identifier: MPL-2.0
+# Copyright (c) 2026 Jonathan D.A. Jewell (hyperpolymath) <j.d.a.jewell@open.ac.uk>
+#
+# rsr-profile.a2ml — RSR template-applicability profile for arghda-core.
+#
+# Declares which template capabilities this repo has, so its scaffold can be
+# checked against the gate model instead of a fixed "one shape fits all".
+# Policy:  hyperpolymath/standards TEMPLATE-APPLICABILITY-POLICY.adoc
+# Data:    hyperpolymath/standards .machine_readable/template-capability-gates.toml
+# Checker: hyperpolymath/standards scripts/check-rsr-profile.sh
+
+[profile]
+preset = "rust-cli"
+add = []      # extra capabilities beyond the preset
+remove = []   # preset capabilities this repo does NOT have
+
+[rationale]
+# Why arghda-core declines the maximal template's gated modules:
+no-abi = "language-agnostic engine; no C-ABI/FFI seam, no Idris2 ABI proofs (no abi.ipkg / src/interface/)"
+no-formal-proofs = "consumes Agda — shells out to agda / agda-unused — but contains no in-tree proofs (no verification/proofs/)"
+no-container = "ships a CLI binary, not a container image"
+no-reproducible-build = "cargo build only for now; guix.scm / flake.nix are a future addition, not present"
+no-affinescript = "pure Rust; the planned AffineScript visual layer is a separate repo (arghda-studio)"
+no-governance-tier = "leaf tool; declines the full AUDIT / AFFIRMATION / GOVERNANCE / MAINTAINERS trio"