feat(presets): pluggable preset system with template/command overrides, catalog, and resolver

- Rename 'template packs' to 'presets' to avoid naming collision with core templates
- PresetManifest, PresetRegistry, PresetManager, PresetCatalog, PresetResolver in presets.py
- Extract CommandRegistrar to agents.py as shared infrastructure
- CLI: specify preset list/add/remove/search/resolve/info
- CLI: specify preset catalog list/add/remove
- --preset option on specify init
- Priority-based preset stacking (--priority, lower = higher precedence)
- Command overrides registered into all detected agent directories (17+ agents)
- Extension command safety: skip registration if target extension not installed
- Multi-catalog support: env var, project config, user config, built-in defaults
- resolve_template() / Resolve-Template in bash/PowerShell scripts
- Self-test preset: overrides all 6 core templates + 1 command
- Scaffold with 4 examples: core/extension template and command overrides
- Preset catalog (catalog.json, catalog.community.json)
- Documentation: README.md, ARCHITECTURE.md, PUBLISHING.md
- 110 preset tests, 253 total tests passing

templates/catalog.community.json

@@ -1,6 +0,0 @@
-{
-  "schema_version": "1.0",
-  "updated_at": "2026-03-09T00:00:00Z",
-  "catalog_url": "https://raw.githubusercontent.com/github/spec-kit/main/templates/catalog.community.json",
-  "template_packs": {}
-}

templates/catalog.json

@@ -1,6 +0,0 @@
-{
-  "schema_version": "1.0",
-  "updated_at": "2026-03-09T00:00:00Z",
-  "catalog_url": "https://raw.githubusercontent.com/github/spec-kit/main/templates/catalog.json",
-  "template_packs": {}
-}

templates/template/README.md

@@ -1,49 +0,0 @@
-# My Template Pack
-
-A custom template pack for Spec Kit.
-
-## Overview
-
-This template pack provides customized artifact templates for your development workflow.
-
-## Templates Included
-
-| Template | Type | Description |
-|----------|------|-------------|
-| `spec-template` | artifact | Custom feature specification template |
-
-## Installation
-
-```bash
-# Install from local directory (during development)
-specify template add --dev /path/to/this/directory
-
-# Install from catalog (after publishing)
-specify template add my-template-pack
-```
-
-## Usage
-
-Once installed, templates are automatically resolved by the Spec Kit scripts.
-When you run `specify specify` or create a new feature, your custom templates
-will be used instead of the core defaults.
-
-## Template Types
-
-- **artifact** — Document scaffolds (spec.md, plan.md, tasks.md, etc.)
-- **command** — AI agent prompts (the files in `.claude/commands/`, etc.)
-- **script** — Custom scripts that replace core scripts
-
-## Development
-
-1. Edit templates in the `templates/` directory
-2. Test with: `specify template add --dev .`
-3. Verify with: `specify template resolve spec-template`
-
-## Publishing
-
-See the [Template Publishing Guide](../../docs/TEMPLATE-PUBLISHING-GUIDE.md) for details.
-
-## License
-
-MIT

templates/template/template-pack.yml

@@ -1,66 +0,0 @@
-schema_version: "1.0"
-
-template_pack:
-  # CUSTOMIZE: Change 'my-template-pack' to your template pack ID (lowercase, hyphen-separated)
-  id: "my-template-pack"
-
-  # CUSTOMIZE: Human-readable name for your template pack
-  name: "My Template Pack"
-
-  # CUSTOMIZE: Update version when releasing (semantic versioning: X.Y.Z)
-  version: "1.0.0"
-
-  # CUSTOMIZE: Brief description (under 200 characters)
-  description: "Brief description of what your template pack provides"
-
-  # CUSTOMIZE: Your name or organization name
-  author: "Your Name"
-
-  # CUSTOMIZE: GitHub repository URL (create before publishing)
-  repository: "https://github.com/your-org/spec-kit-templates-my-pack"
-
-  # REVIEW: License (MIT is recommended for open source)
-  license: "MIT"
-
-# Requirements for this template pack
-requires:
-  # CUSTOMIZE: Minimum spec-kit version required
-  speckit_version: ">=0.1.0"
-
-# Templates provided by this pack
-provides:
-  templates:
-    # CUSTOMIZE: Define your artifact templates
-    # Artifact templates are document scaffolds (spec.md, plan.md, etc.)
-    - type: "artifact"
-      name: "spec-template"
-      file: "templates/spec-template.md"
-      description: "Custom feature specification template"
-      replaces: "spec-template"  # Which core template this overrides (optional)
-
-    # ADD MORE TEMPLATES: Copy this block for each template
-    # - type: "artifact"
-    #   name: "plan-template"
-    #   file: "templates/plan-template.md"
-    #   description: "Custom plan template"
-    #   replaces: "plan-template"
-
-    # Command templates (AI agent prompts)
-    # - type: "command"
-    #   name: "specify"
-    #   file: "commands/specify.md"
-    #   description: "Custom specification command"
-    #   replaces: "specify"
-
-    # Script templates
-    # - type: "script"
-    #   name: "create-new-feature"
-    #   file: "scripts/bash/create-new-feature.sh"
-    #   description: "Custom feature creation script"
-    #   replaces: "create-new-feature"
-
-# CUSTOMIZE: Add relevant tags (2-5 recommended)
-# Used for discovery in catalog
-tags:
-  - "example"
-  - "template"

templates/template/templates/spec-template.md

@@ -1,21 +0,0 @@
-# Feature Specification
-
-> Replace this with your actual specification content.
-
-## Overview
-
-Brief description of the feature.
-
-## Requirements
-
-- Requirement 1
-- Requirement 2
-
-## Design
-
-Describe the design approach.
-
-## Acceptance Criteria
-
-- [ ] Criterion 1
-- [ ] Criterion 2