feat(web): inline-expand summary + Q&A in the list (ADR-031, #16)

Click a summarized card → its full summary (summaryBody) + chat dock (chatReveal)
expand in place via HTMX (GET /v/{id}/expand → expandedCard), collapse back via
GET /v/{id}/card → compact VideoCard. Same <li id>, outerHTML swap — the existing
list-fragment pattern. The card title carries href=/v/{id} as the no-JS fallback
(detail page stays for no-JS + deep links); only summarized cards expand. Reuses
summaryBody + chatReveal so the expanded card never drifts from the detail page.

BDD: inline_expand.feature un-pended + mapped. TDD: 6 handler/fragment tests
(expand/collapse fragments, chat dock, summarized-only, no-JS href, shared body).
Minimal CSS only — the TUI/charm restyle is #17.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

internal/web/view.go

@@ -190,6 +190,18 @@ func chatURL(videoID string) templ.SafeURL {
 	return templ.SafeURL("/v/" + videoID + "/chat")
 }
 
+// expandURL builds the inline-expand fragment path (GET) — the full summary + chat
+// dock swapped into the list card in place (ADR-031).
+func expandURL(videoID string) templ.SafeURL {
+	return templ.SafeURL("/v/" + videoID + "/expand")
+}
+
+// cardURL builds the compact-card fragment path (GET) — the collapse target that
+// returns an expanded card to its compact form (ADR-031).
+func cardURL(videoID string) templ.SafeURL {
+	return templ.SafeURL("/v/" + videoID + "/card")
+}
+
 // Charmbracelet-inspired palette for the summarizing animation (TapirSpinner) —
 // a charm purple box, pink tapir, mint snout/eyes/progress. Kept as named consts
 // so the inline span colours and the CSS track/fill share one source of truth.
@@ -618,6 +630,10 @@ a.btn, a.btn:visited { color: var(--accent-fg); }
 .card-meta { color: var(--muted); font-size: .85rem; }
 .card-preview { color: var(--muted); font-size: .9rem; line-height: 1.5; display: -webkit-box; -webkit-line-clamp: 1; line-clamp: 1; -webkit-box-orient: vertical; overflow: hidden; }
 .card-foot { display: flex; gap: var(--s2); align-items: center; flex-wrap: wrap; margin-top: var(--s1); }
+/* Inline-expanded card (ADR-031). Minimal layout only — the TUI/charm restyle is #17. */
+.card-expanded { border-color: var(--accent, #7653fc); }
+.card-expanded-head { display: flex; justify-content: space-between; align-items: baseline; gap: var(--s2); }
+.card-collapse { font-size: .85rem; white-space: nowrap; }
 .chip { display: inline-block; padding: .15rem .55rem; border-radius: 999px; background: var(--accent-weak); color: var(--accent); font-size: .72rem; font-weight: 600; }
 /* passive "retrying later" chip: dim/grey (CharmDim), not the accent — it is a
    status, not an action the user can take. */