feat: Reader mode via Mozilla Readability.js

Adds an opt-in 'Reader mode' advanced option to the capture dialog.
When enabled, Readability.js is injected as a browser script during
SingleFile capture; it fires on single-file-on-before-capture-start,
replaces the page body with the distilled article content, injects a
clean typographic stylesheet, and adds a header with title/byline/site.
Falls back silently if Readability fails (e.g. non-article pages).

- vendor/readability/Readability.js  Apache 2.0, Mozilla, v0.6.0
- singlefile.rs: embed READABILITY_JS + READER_MODE_WRAPPER_JS via
  include_str!; write both to temp dir when reader_mode is true;
  base_single_file_cmd now accepts &[&Path] for multiple --browser-script
- capture.rs: CaptureConfig.reader_mode: bool
- routes.rs: CaptureBody.reader_mode: Option<bool> (defaults false)
- api.js: submitCapture passes reader_mode in payload
- CaptureDialog.jsx: Reader mode toggle in Advanced options (off by default)

frontend/src/api.js

@@ -98,9 +98,10 @@ export async function fetchTags(archiveId) {
 export async function submitCapture(archiveId, locator, quality = null, extensions = null) {
   const payload = { locator }
   if (quality && quality !== 'best') payload.quality = quality
-  // extensions: { ublock_enabled?: bool } — per-capture overrides
-  if (extensions && typeof extensions.ublock_enabled === 'boolean') {
-    payload.ublock_enabled = extensions.ublock_enabled
+  // extensions: { ublock_enabled?: bool, reader_mode?: bool } — per-capture overrides
+  if (extensions) {
+    if (typeof extensions.ublock_enabled === 'boolean') payload.ublock_enabled = extensions.ublock_enabled
+    if (typeof extensions.reader_mode === 'boolean') payload.reader_mode = extensions.reader_mode
   }
   const res = await fetch(`/api/archives/${archiveId}/captures`, {
     method: "POST",

frontend/src/components/CaptureDialog.jsx

@@ -128,6 +128,8 @@ export default function CaptureDialog({ open, archiveId, onClose, onCaptured, on
 
   // Effective uBlock for this session
   const ublockEnabled = ublockOverride !== null ? ublockOverride : (globalUblock ?? true)
+  // Reader mode: off by default, per-session only
+  const [readerMode, setReaderMode] = useState(false)
 
   // On mount: clean up old single-locator sessionStorage keys; reconnect running jobs
   useEffect(() => {
@@ -240,7 +242,7 @@ export default function CaptureDialog({ open, archiveId, onClose, onCaptured, on
     const qual = item.quality || 'best'
     setItems(prev => prev.map(it => it.id === item.id ? { ...it, status: 'submitting', error: null } : it))
     try {
-      const extensions = { ublock_enabled: ublockEnabled }
+      const extensions = { ublock_enabled: ublockEnabled, reader_mode: readerMode }
       const job = await submitCapture(aid, loc, qual, extensions)
       setItems(prev => prev.map(it =>
         it.id === item.id ? { ...it, status: 'running', jobUid: job.job_uid, archiveId: aid } : it
@@ -395,6 +397,22 @@ export default function CaptureDialog({ open, archiveId, onClose, onCaptured, on
                   <span className="ext-toggle-knob" />
                 </button>
               </label>
+              <label className="capture-ext-row" style={{ marginTop: 8 }}>
+                <span className="capture-ext-label">
+                  <span className="capture-ext-name">Reader mode</span>
+                  <span className="capture-ext-desc">Distil to article text via Readability (off by default)</span>
+                </span>
+                <button
+                  type="button"
+                  role="switch"
+                  aria-checked={readerMode}
+                  className={`ext-toggle ext-toggle--sm${readerMode ? ' ext-toggle--on' : ''}`}
+                  onClick={() => setReaderMode(v => !v)}
+                  aria-label="Toggle reader mode for this capture"
+                >
+                  <span className="ext-toggle-knob" />
+                </button>
+              </label>
             </div>
           )}
         </div>