docs+install: post-rename docs polish, install script, d2 architecture diagram (#26)

* docs: add sanderling bird artwork to README and docs index

* chore: add one-line install script for macOS and Linux

Detects os/arch, resolves latest (or pre-)release, verifies sha256,
and installs the binary into $HOME/.sanderling/bin.

* docs: use the one-line installer in getting-started

Replaces the broken `<version>` placeholder snippets with the
install.sh one-liner.

* docs: drop filler line under the install one-liner

* docs: rename index heading to Sanderling Manual

* docs(style): adopt JetBrains Mono and uppercase brand mark

* docs(getting-started): use justfile flow for folio sample

* docs(writing-specs): drop 'coming soon' notes for eventually and implies

* docs(inspect): rewrite layout for tabbed state panels and metrics chart

* docs(inspect): add UI screenshot

* docs: add Inspect to sidebar and index

* docs: restore mermaid bootstrap script in page template

* docs(style): constrain article images to content width

* docs(inspect): drop layout prose, keep what the screenshot doesn't show

* docs(architecture): add d2 source for architecture diagram

Replaces the in-page mermaid block with a d2-rendered SVG. Generated
outputs (svg/png) stay out of git; only the .d2 source is checked in.

* build(docs): render d2 diagrams into build/site/_assets/diagrams

* docs(architecture): swap mermaid block for rendered d2 svg

* ci(docs): install d2 before building the site

* docs(architecture): tighten layout and reroute label-crossing edges

Flip device/sidecar order so trace writer drops cleanly to runs/
without cutting through the JVM cell, right-align the inspect row
via a pad column, and tune grid gaps to keep gRPC and Unix socket
labels off the SANDERLING boundary.

docs/development/architecture.md

@@ -6,30 +6,7 @@ title: Architecture
 
 Three processes, two transports.
 
-```mermaid
-flowchart TB
-    subgraph Go["sanderling (Go)"]
-        Bundler[Bundler<br/>esbuild] --> Verifier[Verifier<br/>goja + LTL]
-        Verifier <--> Runner[Runner]
-        Runner --> Trace[Trace writer<br/>JSONL + PNG]
-        Runner <--> Driver[Driver iface]
-    end
-
-    subgraph Sidecar["Maestro Sidecar (JVM)"]
-        Maestro[maestro-client]
-    end
-
-    subgraph Device["Emulator"]
-        subgraph App["Android app (debug)"]
-            SDK[sanderling-sdk<br/>pause / hierarchy<br/>logs / coverage]
-        end
-    end
-
-    Driver -- gRPC --> Maestro
-    Maestro -- UIAutomator --> App
-    Runner -- Unix socket --> SDK
-    Trace --> Runs[(runs/)]
-```
+<img src="../_assets/diagrams/architecture.svg" alt="sanderling architecture" />
 
 ## Processes
 
@@ -48,6 +25,10 @@ flowchart TB
 
 The split exists for one reason: only real UI events need the cost of crossing process and OS-API boundaries. Introspection is cheap, frequent, and lives on a fast local socket directly to the app.
 
+## Inspect UI
+
+`sanderling inspect` is a separate mode of the same Go binary. It serves an embedded React bundle and reads `runs/` from disk, streaming file-watcher events over SSE so the UI updates as new steps land. It has no connection to the sidecar or the SDK; it only consumes the trace artifacts.
+
 ## Per-step cycle
 
 The heart of the system is: