docs: expand root README (env vars, PWA, InfraLens docs, e2e coverage)

- document the real env vars (RESEND_API_KEY, CONTACT_EMAIL, Upstash) with
  their graceful fallbacks, previously undocumented
- add api-studio to the Project Structure tree, missed since v1.5.0/v1.6.0
- correct pnpm e2e's description — it covers everything except InfraLens,
  not just "portfolio routes"
- fix wording that implied every /tools tool is open-source, when only
  InfraLens carries a license
- link docs/infralens's CONTRIBUTING and SECURITY, previously unlinked
- mention the installable PWA (manifest + service worker)

Author: Randy-R-code

README.md

@@ -13,7 +13,7 @@ The homepage is an interactive world map: each zone is a real, accessible
 route (Projects, Tools, Articles, About, Lab), not just a visual gimmick.
 Beyond the map, the site is a standard content/portfolio app — project case
 studies, a blog, a contact form, and a growing space for developer tools
-built and open-sourced under the Randy Code brand.
+built under the Randy Code brand.
 
 ## Highlights
 
@@ -24,8 +24,12 @@ built and open-sourced under the Randy Code brand.
   write-ups sourced from the real product, not marketing copy.
 - **Articles** (`/articles`) — technical write-ups grounded in what was
   actually built (e.g. securing a URL analyzer against SSRF), with an RSS feed.
-- **Developer tools** (`/tools`) — open-source tools built by Randy Code,
-  usable directly from the site.
+- **Developer tools** (`/tools`) — five focused tools built by Randy Code
+  and usable directly from the site (InfraLens, API Studio, Cron Builder,
+  JSON Studio, MetaLens); InfraLens is the one released under an
+  open-source license.
+- **PWA** — installable from the browser, with a web app manifest and a
+  cache-first service worker (`public/sw.js`) for offline resilience.
 
 ## Developer Tools — InfraLens
 
@@ -35,8 +39,12 @@ public technical signals, summarized into one scored, readable report.
 
 It's the first tool integrated natively into Randy Code (migrated from its
 own standalone repository into `app/tools/infralens/` and `src/infralens/`).
-Its original documentation, changelog, and MIT license are preserved under
-[`docs/infralens/`](docs/infralens/README.md).
+Its original docs are preserved under `docs/infralens/`:
+[README](docs/infralens/README.md),
+[CHANGELOG](docs/infralens/CHANGELOG.md),
+[CONTRIBUTING](docs/infralens/CONTRIBUTING.md),
+[SECURITY](docs/infralens/SECURITY.md), and
+[LICENSE](docs/infralens/LICENSE).
 
 ## Tech Stack
 
@@ -63,9 +71,11 @@ app/
   projects/                   # Project case studies (listing + [slug])
   tools/                      # Developer tools
     infralens/                # InfraLens — native routes (analyze, compare, docs, privacy)
+    api-studio/               # API Studio — HTTP request client + webhook inspector
     cron-builder/             # Cron Builder — visual cron expression editor
     json-studio/              # JSON Studio — format, validate and explore JSON
     metalens/                 # MetaLens — inspect page metadata, OG/Twitter cards, indexing signals
+  api/api-studio/             # Route Handlers — outbound proxy + webhook ingestion
   rss.xml/                    # RSS feed
   sitemap.ts, robots.ts, manifest.ts, opengraph-image.tsx
 
@@ -74,6 +84,7 @@ src/
   components/                 # Shared UI (map, layout, shadcn/ui primitives)
   lib/                        # Content registries, brand tokens, navigation, JSON-LD
   infralens/                  # InfraLens engine — checks, security/SSRF, DNS, scoring, history
+  api-studio/                 # API Studio engine — request execution, codegen, history, webhooks
   cron-builder/               # Cron Builder engine — parsing, validation, next-run calculation
   json-studio/                # JSON Studio engine — parsing, formatting, stats, storage
   metalens/                   # MetaLens engine — HTML parsing, URL resolution, findings
@@ -93,6 +104,18 @@ pnpm dev
 
 Open [http://localhost:3000](http://localhost:3000).
 
+### Environment Variables
+
+None are required just to browse the site locally — everything below has a
+graceful fallback. Set them in `.env.local` to exercise the real behavior:
+
+- `RESEND_API_KEY` — sends real email from the contact form; without it,
+  submissions fail.
+- `CONTACT_EMAIL` — destination address for contact form submissions.
+- `UPSTASH_REDIS_REST_URL`, `UPSTASH_REDIS_REST_TOKEN` — enable real rate
+  limiting (InfraLens, MetaLens, contact form, API Studio); without them,
+  the shared limiter (`src/lib/rate-limit/`) runs allow-all.
+
 ## Quality Checks
 
 ```bash
@@ -102,7 +125,7 @@ pnpm test        # Vitest
 pnpm build       # Production build
 pnpm check       # lint + typecheck + test + build — the required local/CI gate
 
-pnpm e2e             # Playwright — portfolio routes
+pnpm e2e             # Playwright — everything except InfraLens (portfolio + API Studio, Cron Builder, JSON Studio, MetaLens)
 pnpm e2e:infralens   # Playwright — InfraLens (rate-limited, single worker)
 ```