Add a `.prompt` resource role for language-model prompts (OVOS-INTENT-2 V3)

Tracking issue for PR #4 — OVOS-INTENT-2 v3: the .prompt resource role

Local and hosted language models are now ubiquitous. The prompt a skill sends to that model is a first-class skill resource and, like every other resource, should be localizable: shipped per language, overridable, resolved through the same precedence chain. The current OVOS-INTENT-2 resource roles have no place for it.

Proposal

Add a sixth resource role to OVOS-INTENT-2 — .prompt — taking the spec to version 3.

A .prompt lives under locale/<lang>/ like any other resource and differs from .dialog in three deliberate ways:

1. Whole-file — the entire file content, verbatim, is one prompt.
2. Plain text, not a template — no OVOS-INTENT-1 grammar. The only special construct is {name} substitution.
3. Conservative slots — {name} is substituted only when well-formed, supplied, and not inside a fenced code block (CommonMark-aligned). HTML-style <!-- … --> comments are stripped before the prompt reaches the model. Unfilled slots remain as literal text.

V3 is additive over V2.

Start by reviewing PR #4 and the existing OVOS-INTENT-2 V2 resource-role specification. Confirm how the proposed .prompt role, localization, precedence, substitution rules, fenced-code handling, and comment stripping should be represented; done means the architecture specification is updated to a consistent V3.