chore(release): clean up repo for v0.0.1 release

Excluded from release bundle:
- CONTEXT.md, CHANGELOG.md (agent/project working notes)
- client-app/ (React Native messenger — tracked separately)
- contracts/hello_go/ (unused standalone example)

Kept contracts/counter/ and contracts/name_registry/ as vm-test fixtures
(referenced by vm/vm_test.go; NOT production contracts).

Docs refactor:
- docs/README.md — new top-level index with cross-references
- docs/quickstart.md — rewrite around single-node as primary path
- docs/node/README.md — full rewrite, all CLI flags, schema table
- docs/api/README.md — add /api/well-known-version, /api/update-check
- docs/contracts/README.md — split native (Go) vs WASM (user-deployable)
- docs/update-system.md — new, full 5-layer update system design
- README.md — link into docs/, drop CHANGELOG/client-app references

Build-time version system (inherited from earlier commits this branch):
- node --version / client --version with ldflags-injected metadata
- /api/well-known-version with {build, protocol_version, features[]}
- Peer-version gossip on dchain/version/v1
- /api/update-check against Gitea release API
- deploy/single/update.sh with semver guard + 15-min systemd jitter

contracts/hello_go/hello_go_abi.json

@@ -1,38 +0,0 @@
-{
-  "contract": "hello_go",
-  "version": "1.0.0",
-  "description": "Example DChain contract written in Go (TinyGo SDK). Demonstrates counter, owner-gated reset, string args, and inter-contract calls.",
-  "build": "tinygo build -o hello_go.wasm -target wasip1 -no-debug .",
-  "methods": [
-    {
-      "name": "increment",
-      "description": "Add 1 to the counter. Logs 'counter: N'.",
-      "args": []
-    },
-    {
-      "name": "get",
-      "description": "Log the current counter value without changing state.",
-      "args": []
-    },
-    {
-      "name": "reset",
-      "description": "Reset counter to 0. First caller becomes the owner; only owner can reset.",
-      "args": []
-    },
-    {
-      "name": "greet",
-      "description": "Log a greeting. Logs 'hello, <name>! block=N'.",
-      "args": [
-        {"name": "name", "type": "string", "description": "Name to greet (defaults to 'world')"}
-      ]
-    },
-    {
-      "name": "ping",
-      "description": "Call a method on another contract (inter-contract call demo).",
-      "args": [
-        {"name": "contract_id", "type": "string", "description": "Target contract ID"},
-        {"name": "method",      "type": "string", "description": "Method to call on target"}
-      ]
-    }
-  ]
-}

contracts/hello_go/main.go

@@ -1,104 +0,0 @@
-// Package main is an example DChain smart contract written in Go.
-//
-// # Build
-//
-//	tinygo build -o hello_go.wasm -target wasip1 -no-debug .
-//
-// # Deploy
-//
-//	client deploy-contract --key /keys/node1.json \
-//	    --wasm hello_go.wasm --abi hello_go_abi.json \
-//	    --node http://localhost:8081
-//
-// # Use
-//
-//	client call-contract --key /keys/node1.json --contract $ID \
-//	    --method increment --gas 5000 --node http://localhost:8081
-//
-// The contract implements a simple counter with owner-gated reset.
-// It demonstrates every SDK primitive: arguments, state, caller, logging,
-// and inter-contract calls.
-package main
-
-import (
-	"strconv"
-
-	dc "go-blockchain/contracts/sdk"
-)
-
-// increment adds 1 to the counter and logs the new value.
-//
-//export increment
-func increment() {
-	v := dc.GetU64("counter")
-	v++
-	dc.PutU64("counter", v)
-	dc.Log("counter: " + strconv.FormatUint(v, 10))
-}
-
-// get logs the current counter value without changing state.
-//
-//export get
-func get() {
-	v := dc.GetU64("counter")
-	dc.Log("counter: " + strconv.FormatUint(v, 10))
-}
-
-// reset sets the counter to 0. On first call the caller becomes the owner.
-// Subsequent calls are restricted to the owner.
-//
-//export reset
-func reset() {
-	owner := dc.GetStateStr("owner")
-	caller := dc.Caller()
-	if owner == "" {
-		dc.SetStateStr("owner", caller)
-		dc.PutU64("counter", 0)
-		dc.Log("initialized — owner: " + caller[:min8(caller)])
-		return
-	}
-	if caller != owner {
-		dc.Log("unauthorized: " + caller[:min8(caller)])
-		return
-	}
-	dc.PutU64("counter", 0)
-	dc.Log("reset by owner")
-}
-
-// greet logs a personalised greeting using the first call argument.
-//
-//export greet
-func greet() {
-	name := dc.ArgStr(0, 64)
-	if name == "" {
-		name = "world"
-	}
-	dc.Log("hello, " + name + "! block=" + strconv.FormatUint(dc.BlockHeight(), 10))
-}
-
-// ping calls another contract's method (demonstrates inter-contract calls).
-// Args: contract_id (string), method (string)
-//
-//export ping
-func ping() {
-	target := dc.ArgStr(0, 64)
-	method := dc.ArgStr(1, 64)
-	if target == "" || method == "" {
-		dc.Log("ping: target and method required")
-		return
-	}
-	if dc.CallContract(target, method, "[]") {
-		dc.Log("ping: " + method + " ok")
-	} else {
-		dc.Log("ping: " + method + " failed")
-	}
-}
-
-func min8(s string) int {
-	if len(s) < 8 {
-		return len(s)
-	}
-	return 8
-}
-
-func main() {}