frontend: nest asset output under dist/static/

The src/index.html / src/stats.html files reference assets at URLs
like /static/app.js, /static/dashboard.css. The initial Phase 1 build
flattened everything to dist/{app.js, dashboard.css, ...} which would
have forced the Phase 4 Rust ServeDir mount to do URL rewriting just
to make the existing HTML references resolve.

Rework: bundles now write to dist/static/, HTML stays at dist/ top
level. Layout matches the URLs the HTML uses, so the Phase 4 mount
is the simplest possible `fallback_service(ServeDir::new(dist))`.

No source-file changes — just the esbuild outfile/outdir paths.
Rebuilt; verified asset filenames + sizes unchanged.

Refs #273.

frontend/packages/agent/build.mjs

@@ -1,18 +1,21 @@
-// esbuild build for @hive/agent. Outputs:
+// esbuild build for @hive/agent. Output layout (`dist/`):
 //
-//   dist/app.js        bundled ES module (entrypoint = src/app.js,
+//   dist/index.html            served at GET /
+//   dist/stats.html            served at GET /stats
+//   dist/screen.html           served at GET /screen
+//   dist/static/app.js         served at /static/app.js (ESM bundle,
 //                               pulls in @hive/shared + marked)
-//   dist/agent.css     bundled stylesheet (entrypoint = src/agent.css,
+//   dist/static/app.js.map     source map sibling
-//                       @import "@hive/shared/base.css" + terminal.css
+//   dist/static/stats.js       served at /static/stats.js (pulls in
-//                       get inlined here)
+//                               chart.js/auto)
-//   dist/stats.js      bundled stats page (entrypoint = src/stats.js,
+//   dist/static/stats.js.map   source map sibling
-//                       pulls in chart.js/auto)
+//   dist/static/agent.css      served at /static/agent.css (@import
-//   dist/{index,stats,screen}.html  copies of src/*.html (esbuild
+//                               resolved from @hive/shared)
-//                       doesn't process HTML; the bundled siblings are
-//                       referenced by name)
 //
-// The in-container Rust binary serves `dist/` via tower_http::ServeDir,
+// The in-container Rust binary mounts `dist/` (with per-agent
-// with the per-agent `hyperhive.frontend.extraFiles` layered on top.
+// `hyperhive.frontend.extraFiles` layered on top) as a
+// `tower_http::ServeDir` fallback; the layout above keeps every URL
+// the HTML references reachable without rewriting paths.
 
 import { build } from 'esbuild';
 import { mkdirSync, copyFileSync, rmSync } from 'node:fs';
@@ -22,15 +25,16 @@ import { fileURLToPath } from 'node:url';
 const here = dirname(fileURLToPath(import.meta.url));
 const src = (p) => resolve(here, 'src', p);
 const dist = (p) => resolve(here, 'dist', p);
+const staticDir = (p) => resolve(here, 'dist', 'static', p);
 
 rmSync(dist(''), { recursive: true, force: true });
-mkdirSync(dist(''), { recursive: true });
+mkdirSync(staticDir(''), { recursive: true });
 
 // Two JS entries: the main app + the stats page. Both bundle their
 // own deps so each page can be loaded independently.
 await build({
   entryPoints: [src('app.js'), src('stats.js')],
-  outdir: dist(''),
+  outdir: staticDir(''),
   bundle: true,
   format: 'esm',
   platform: 'browser',
@@ -43,7 +47,7 @@ await build({
 // shared/terminal.css from the @hive/shared workspace dep.
 await build({
   entryPoints: [src('agent.css')],
-  outfile: dist('agent.css'),
+  outfile: staticDir('agent.css'),
   bundle: true,
   loader: { '.css': 'css' },
   logLevel: 'info',

frontend/packages/dashboard/build.mjs

@@ -1,17 +1,15 @@
-// esbuild build for @hive/dashboard. Outputs:
+// esbuild build for @hive/dashboard. Output layout (`dist/`):
 //
-//   dist/app.js          bundled ES module (entrypoint = src/app.js,
+//   dist/index.html               served by the Rust router at GET /
+//   dist/static/app.js            served at /static/app.js (ESM bundle,
 //                                  pulls in @hive/shared + marked)
-//   dist/dashboard.css   bundled stylesheet (entrypoint = src/dashboard.css,
+//   dist/static/app.js.map        source map sibling
-//                        @import "@hive/shared/base.css" + terminal.css
+//   dist/static/dashboard.css     served at /static/dashboard.css
-//                        get inlined here)
+//                                  (@import resolved from @hive/shared)
-//   dist/index.html      copy of src/index.html (esbuild doesn't process
-//                        HTML; the script/link tags reference the bundled
-//                        siblings by name)
 //
-// Both Rust binaries serve `dist/` via tower_http::ServeDir. The output
+// The Rust binary mounts `dist/` as a `tower_http::ServeDir` fallback;
-// must keep the same filenames the existing index.html references, so
+// the layout above keeps every URL the index.html references reachable
-// downstream changes are mechanical.
+// without rewriting paths in the HTML.
 
 import { build } from 'esbuild';
 import { mkdirSync, copyFileSync, rmSync } from 'node:fs';
@@ -21,16 +19,17 @@ import { fileURLToPath } from 'node:url';
 const here = dirname(fileURLToPath(import.meta.url));
 const src = (p) => resolve(here, 'src', p);
 const dist = (p) => resolve(here, 'dist', p);
+const staticDir = (p) => resolve(here, 'dist', 'static', p);
 
 rmSync(dist(''), { recursive: true, force: true });
-mkdirSync(dist(''), { recursive: true });
+mkdirSync(staticDir(''), { recursive: true });
 
 // Bundle the JS entry. ES-module output, browser target, no minify
 // (line-aligned source aids debugging; minification belongs in a later
 // follow-up once asset sizes warrant it).
 await build({
   entryPoints: [src('app.js')],
-  outfile: dist('app.js'),
+  outfile: staticDir('app.js'),
   bundle: true,
   format: 'esm',
   platform: 'browser',
@@ -43,7 +42,7 @@ await build({
 // re-exports from @hive/shared.
 await build({
   entryPoints: [src('dashboard.css')],
-  outfile: dist('dashboard.css'),
+  outfile: staticDir('dashboard.css'),
   bundle: true,
   loader: { '.css': 'css' },
   logLevel: 'info',