Read a web page when he names one, and watch a few on a timer (#259)

The network fallback behind the local sources, off unless configured.

internal/crawl is pure: a stdlib robots.txt parser (group specificity,
wildcards, Crawl-delay, cached per host), HTML-to-plaintext extraction, and a
watcher that notes a watched page only when its text changed. It has no store
access and no net/http; cmd/mavend/crawls.go is the impure half.

Every limit is code and tested: the guarded fetcher from #258 enforces the host
allowlist/denylist, refuses private addresses in the dialer Control hook (so DNS
rebinding and each redirect hop are covered), caps size and redirects, times out,
and spaces requests per host. A robots.txt Disallow is refused with no override.

On demand, reading is a query source placed last in the chain, after his memory,
his notes, and the local Kiwix ZIMs once those are wired: no URL in the
utterance means no fetch, and only the URL ever leaves the box. Scheduled
watches write notes and announce nothing.

The vendored tree has no x/net/html, goquery or temoto/robotstxt, so the parsers
are stdlib. No new dependency.

cmd/mavend/actions_query.go

@@ -8,6 +8,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/kami/maven/internal/crawl"
 	"github.com/kami/maven/internal/ipc"
 	"github.com/kami/maven/internal/memory"
 	"github.com/kami/maven/internal/morning"
@@ -78,6 +79,13 @@ var querySources = []querySource{
 	{"embed", (*reactiveHandler).queryEmbed},
 	{"memory", (*reactiveHandler).queryMemory},
 	{"notes", (*reactiveHandler).queryNotes},
+	// LAST before the model answers from memory, and that position is the whole
+	// design (Vikunja #259): local sources first. The model, his own notes and
+	// facts, and — once internal/kiwix is wired into this chain — the offline
+	// ZIMs all get their turn before anything touches the network. This source
+	// only claims a turn where he named a URL out loud, so it never competes
+	// with a local answer.
+	{"web", (*reactiveHandler).queryWeb},
 	{"general-knowledge", (*reactiveHandler).queryGeneral},
 }
 
@@ -371,6 +379,57 @@ func (h *reactiveHandler) queryNotes(ctx context.Context, t *queryTurn) (string,
 	return reply, true
 }
 
+// webPageContextRunes — how much of a fetched page is handed to the phraser.
+// Less than the crawler keeps: the rest of the 4096-token window belongs to the
+// prompt, the persona block and the reply.
+const webPageContextRunes = 1500
+
+// queryWeb — "посмотри https://example.org/x — что там?" (Vikunja #259).
+//
+// It claims a turn ONLY when he named a URL, which is what keeps a fallback from
+// becoming a habit: no URL, no fetch, and the model answers from what is local.
+// What leaves the box is the URL and nothing else — no note, no fact, no history
+// travels with it.
+func (h *reactiveHandler) queryWeb(ctx context.Context, t *queryTurn) (string, bool) {
+	link, ok := router.FirstURL(t.dec.Utterance)
+	if !ok {
+		return "", false
+	}
+	if h.crawler == nil {
+		// Claim rather than fall through: he asked about a specific page, and
+		// letting the model answer from the URL's spelling alone is how a small
+		// model invents a page's contents.
+		return "я не читаю страницы — это не настроено.", true
+	}
+	ctxFetch, cancel := context.WithTimeout(ctx, 30*time.Second)
+	defer cancel()
+	page, err := h.crawler.Page(ctxFetch, link)
+	if err != nil {
+		if errors.Is(err, crawl.ErrRobots) {
+			return "эта страница закрыта для чтения — robots.txt не разрешает.", true
+		}
+		log.Printf("voice: web: %v", err)
+		return "не получилось прочитать страницу.", true
+	}
+	if page.Text == "" {
+		return "страница открылась, но читать там нечего.", true
+	}
+	// The page is handed to the phraser the same way a note is: as context for
+	// the question he actually asked. She answers the question, she does not
+	// recite the page.
+	snippet := page.Title + "\n" + crawl.TrimRunes(page.Text, webPageContextRunes)
+	reply, perr := h.phraser.PhraseQuery(ctx, t.dec.Utterance, []string{snippet})
+	if perr != nil {
+		log.Printf("voice: web: phrase: %v", perr)
+	}
+	if reply == "" {
+		// No phraser (or it failed): read back the top of the page rather than
+		// pretend the fetch did not happen.
+		return "вот что на странице: " + crawl.TrimRunes(page.Text, 300), true
+	}
+	return reply, true
+}
+
 // queryGeneral — general knowledge from the phraser, the last source before
 // giving up. It always claims: either the model answers or Maven says she
 // doesn't know.