docs: move community extensions table to main README for discoverability (#1959)

- Add 🧩 Community Extensions section to README.md before Community Walkthroughs
- Add table of contents entry for the new section
- Replace extensions/README.md table with a link back to the main README
- Update EXTENSION-PUBLISHING-GUIDE.md references to point to README.md
- Update EXTENSION-DEVELOPMENT-GUIDE.md references to point to README.md

README.md

@@ -22,6 +22,7 @@
 - [🤔 What is Spec-Driven Development?](#-what-is-spec-driven-development)
 - [⚡ Get Started](#-get-started)
 - [📽️ Video Overview](#️-video-overview)
+- [🧩 Community Extensions](#-community-extensions)
 - [🚶 Community Walkthroughs](#-community-walkthroughs)
 - [🛠️ Community Friends](#️-community-friends)
 - [🤖 Supported AI Agents](#-supported-ai-agents)
@@ -156,6 +157,42 @@ Want to see Spec Kit in action? Watch our [video overview](https://www.youtube.c
 
 [![Spec Kit video header](/media/spec-kit-video-header.jpg)](https://www.youtube.com/watch?v=a9eR1xsfvHg&pp=0gcJCckJAYcqIYzv)
 
+## 🧩 Community Extensions
+
+The following community-contributed extensions are available in [`catalog.community.json`](extensions/catalog.community.json):
+
+**Categories:** `docs` — reads, validates, or generates spec artifacts · `code` — reviews, validates, or modifies source code · `process` — orchestrates workflow across phases · `integration` — syncs with external platforms · `visibility` — reports on project health or progress
+
+**Effect:** `Read-only` — produces reports without modifying files · `Read+Write` — modifies files, creates artifacts, or updates specs
+
+| Extension | Purpose | Category | Effect | URL |
+|-----------|---------|----------|--------|-----|
+| Archive Extension | Archive merged features into main project memory. | `docs` | Read+Write | [spec-kit-archive](https://github.com/stn1slv/spec-kit-archive) |
+| Azure DevOps Integration | Sync user stories and tasks to Azure DevOps work items using OAuth authentication | `integration` | Read+Write | [spec-kit-azure-devops](https://github.com/pragya247/spec-kit-azure-devops) |
+| Checkpoint Extension | Commit the changes made during the middle of the implementation, so you don't end up with just one very large commit at the end | `code` | Read+Write | [spec-kit-checkpoint](https://github.com/aaronrsun/spec-kit-checkpoint) |
+| Cleanup Extension | Post-implementation quality gate that reviews changes, fixes small issues (scout rule), creates tasks for medium issues, and generates analysis for large issues | `code` | Read+Write | [spec-kit-cleanup](https://github.com/dsrednicki/spec-kit-cleanup) |
+| Cognitive Squad | Multi-agent cognitive system with Triadic Model: understanding, internalization, application — with quality gates, backpropagation verification, and self-healing | `docs` | Read+Write | [cognitive-squad](https://github.com/Testimonial/cognitive-squad) |
+| Conduct Extension | Orchestrates spec-kit phases via sub-agent delegation to reduce context pollution. | `process` | Read+Write | [spec-kit-conduct-ext](https://github.com/twbrandon7/spec-kit-conduct-ext) |
+| DocGuard — CDD Enforcement | Canonical-Driven Development enforcement. Validates, scores, and traces project documentation with automated checks, AI-driven workflows, and spec-kit hooks. Zero NPM runtime dependencies. | `docs` | Read+Write | [spec-kit-docguard](https://github.com/raccioly/docguard) |
+| Fleet Orchestrator | Orchestrate a full feature lifecycle with human-in-the-loop gates across all SpecKit phases | `process` | Read+Write | [spec-kit-fleet](https://github.com/sharathsatish/spec-kit-fleet) |
+| Iterate | Iterate on spec documents with a two-phase define-and-apply workflow — refine specs mid-implementation and go straight back to building | `docs` | Read+Write | [spec-kit-iterate](https://github.com/imviancagrace/spec-kit-iterate) |
+| Jira Integration | Create Jira Epics, Stories, and Issues from spec-kit specifications and task breakdowns with configurable hierarchy and custom field support | `integration` | Read+Write | [spec-kit-jira](https://github.com/mbachorik/spec-kit-jira) |
+| Learning Extension | Generate educational guides from implementations and enhance clarifications with mentoring context | `docs` | Read+Write | [spec-kit-learn](https://github.com/imviancagrace/spec-kit-learn) |
+| Project Health Check | Diagnose a Spec Kit project and report health issues across structure, agents, features, scripts, extensions, and git | `visibility` | Read-only | [spec-kit-doctor](https://github.com/KhawarHabibKhan/spec-kit-doctor) |
+| Project Status | Show current SDD workflow progress — active feature, artifact status, task completion, workflow phase, and extensions summary | `visibility` | Read-only | [spec-kit-status](https://github.com/KhawarHabibKhan/spec-kit-status) |
+| Ralph Loop | Autonomous implementation loop using AI agent CLI | `code` | Read+Write | [spec-kit-ralph](https://github.com/Rubiss/spec-kit-ralph) |
+| Reconcile Extension | Reconcile implementation drift by surgically updating feature artifacts. | `docs` | Read+Write | [spec-kit-reconcile](https://github.com/stn1slv/spec-kit-reconcile) |
+| Retrospective Extension | Post-implementation retrospective with spec adherence scoring, drift analysis, and human-gated spec updates | `docs` | Read+Write | [spec-kit-retrospective](https://github.com/emi-dm/spec-kit-retrospective) |
+| Review Extension | Post-implementation comprehensive code review with specialized agents for code quality, comments, tests, error handling, type design, and simplification | `code` | Read-only | [spec-kit-review](https://github.com/ismaelJimenez/spec-kit-review) |
+| SDD Utilities | Resume interrupted workflows, validate project health, and verify spec-to-task traceability | `process` | Read+Write | [speckit-utils](https://github.com/mvanhorn/speckit-utils) |
+| Spec Sync | Detect and resolve drift between specs and implementation. AI-assisted resolution with human approval | `docs` | Read+Write | [spec-kit-sync](https://github.com/bgervin/spec-kit-sync) |
+| Understanding | Automated requirements quality analysis — 31 deterministic metrics against IEEE/ISO standards with experimental energy-based ambiguity detection | `docs` | Read-only | [understanding](https://github.com/Testimonial/understanding) |
+| V-Model Extension Pack | Enforces V-Model paired generation of development specs and test specs with full traceability | `docs` | Read+Write | [spec-kit-v-model](https://github.com/leocamello/spec-kit-v-model) |
+| Verify Extension | Post-implementation quality gate that validates implemented code against specification artifacts | `code` | Read-only | [spec-kit-verify](https://github.com/ismaelJimenez/spec-kit-verify) |
+| Verify Tasks Extension | Detect phantom completions: tasks marked [X] in tasks.md with no real implementation | `code` | Read-only | [spec-kit-verify-tasks](https://github.com/datastone-inc/spec-kit-verify-tasks) |
+
+To submit your own extension, see the [Extension Publishing Guide](extensions/EXTENSION-PUBLISHING-GUIDE.md).
+
 ## 🚶 Community Walkthroughs
 
 See Spec-Driven Development in action across different scenarios with these community-contributed walkthroughs:
@@ -391,7 +428,7 @@ specify extension add <extension-name>
 
 For example, extensions could add Jira integration, post-implementation code review, V-Model test traceability, or project health diagnostics.
 
-See the [Extensions README](./extensions/README.md) for the full guide, the complete community catalog, and how to build and publish your own.
+See the [Extensions README](./extensions/README.md) for the full guide and how to build and publish your own. Browse the [community extensions](#-community-extensions) above for what's available.
 
 ### Presets — Customize Existing Workflows