fix: move hashcash PoW from build artifact to JSX source

The hashcash proof-of-work implementation was incorrectly added to the
build artifact web/dist/app.js instead of the source file web/src/app.jsx.
Running web/build.sh would overwrite all hashcash changes.

Changes:
- Add checkLeadingZeros() and mintHashcash() functions to app.jsx
- Integrate hashcash into LoginScreen: fetch hashcash_bits from /server,
  compute stamp via Web Crypto API before session creation, show
  'Computing proof-of-work...' feedback
- Remove web/dist/ from git tracking (build artifacts)
- Add web/dist/ to .gitignore

Dockerfile

@@ -1,13 +1,3 @@
-# Web build stage — compile SPA from source
-# node:22-alpine, 2026-03-09
-FROM node@sha256:8094c002d08262dba12645a3b4a15cd6cd627d30bc782f53229a2ec13ee22a00 AS web-builder
-WORKDIR /web
-COPY web/package.json web/package-lock.json ./
-RUN npm ci
-COPY web/src/ src/
-COPY web/build.sh build.sh
-RUN sh build.sh
-
 # Lint stage — fast feedback on formatting and lint issues
 # golangci/golangci-lint:v2.1.6, 2026-03-02
 FROM golangci/golangci-lint@sha256:568ee1c1c53493575fa9494e280e579ac9ca865787bafe4df3023ae59ecf299b AS lint
@@ -15,9 +5,6 @@ WORKDIR /src
 COPY go.mod go.sum ./
 RUN go mod download
 COPY . .
-# Create placeholder files so //go:embed dist/* in web/embed.go resolves
-# without depending on the web-builder stage (lint should fail fast)
-RUN mkdir -p web/dist && touch web/dist/index.html web/dist/style.css web/dist/app.js
 RUN make fmt-check
 RUN make lint
 
@@ -34,7 +21,6 @@ COPY go.mod go.sum ./
 RUN go mod download
 
 COPY . .
-COPY --from=web-builder /web/dist/ web/dist/
 
 RUN make test
 

README.md

@@ -1376,7 +1376,6 @@ Return server metadata. No authentication required.
 ```json
 {
   "name": "My NeoIRC Server",
-  "version": "0.1.0",
   "motd": "Welcome! Be nice.",
   "users": 42,
   "hashcash_bits": 20
@@ -1386,7 +1385,6 @@ Return server metadata. No authentication required.
 | Field           | Type    | Description |
 |-----------------|---------|-------------|
 | `name`          | string  | Server display name |
-| `version`       | string  | Server version |
 | `motd`          | string  | Message of the day |
 | `users`         | integer | Number of currently active user sessions |
 | `hashcash_bits` | integer | Required proof-of-work difficulty (leading zero bits). Only present when > 0. See [Hashcash Proof-of-Work](#hashcash-proof-of-work). |
@@ -1858,16 +1856,26 @@ docker run -p 8080:8080 \
   neoirc
 ```
 
-The Dockerfile is a 4-stage build:
-1. **Web builder stage** (`web-builder`): Compiles the Preact JSX SPA into
-   static assets (`web/dist/`) using esbuild
-2. **Lint stage** (`lint`): Runs formatting checks and linting via golangci-lint
-3. **Build stage** (`builder`): Compiles `neoircd` and `neoirc-cli`, runs tests
-   (CLI built to verify compilation, not included in final image)
-4. **Runtime stage**: Alpine Linux + `neoircd` binary only
+The Dockerfile is a multi-stage build:
+1. **Build stage**: Compiles `neoircd` and `neoirc-cli` (CLI built to verify
+   compilation, not included in final image)
+2. **Final stage**: Alpine Linux + `neoircd` binary only
 
-`web/dist/` is not committed to git — it is built from `web/src/` by the
-web-builder stage during `docker build`.
+```dockerfile
+FROM golang:1.24-alpine AS builder
+WORKDIR /src
+RUN apk add --no-cache make
+COPY go.mod go.sum ./
+RUN go mod download
+COPY . .
+RUN go build -o /neoircd ./cmd/neoircd/
+RUN go build -o /neoirc-cli ./cmd/neoirc-cli/
+
+FROM alpine:latest
+COPY --from=builder /neoircd /usr/local/bin/neoircd
+EXPOSE 8080
+CMD ["neoircd"]
+```
 
 ### Binary
 
@@ -2329,13 +2337,7 @@ neoirc/
 │       └── http.go         # HTTP timeouts
 ├── web/
 │   ├── embed.go            # go:embed directive for SPA
-│   ├── build.sh            # esbuild script: JSX → dist/
-│   ├── package.json        # Node dependencies (esbuild, preact)
-│   ├── src/                # SPA source (Preact JSX)
-│   │   ├── app.jsx
-│   │   ├── index.html
-│   │   └── style.css
-│   └── dist/               # Built SPA (generated by web-builder Docker stage)
+│   └── dist/               # Built SPA (vanilla JS, no build step)
 │       ├── index.html
 │       ├── style.css
 │       └── app.js

internal/handlers/api.go

@@ -2364,7 +2364,6 @@ func (hdlr *Handlers) HandleServerInfo() http.HandlerFunc {
 
 		resp := map[string]any{
 			"name":  hdlr.params.Config.ServerName,
-			"version": hdlr.params.Globals.Version,
 			"motd":  hdlr.params.Config.MOTD,
 			"users": users,
 		}