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>

docs/use-cases/inline_expand.feature

@@ -4,39 +4,33 @@ Feature: Inline-expand summary + Q&A in the list (ADR-031, #16)
   So that I get the full read and follow-up without leaving the list (SPA-like, no page hop)
 
   # HTMX inline-expand, no SPA framework (ADR-031). Each scenario maps to a Go test
-  # in scenario_coverage_test.go; tagged @pending until the TDD step lands it.
+  # in scenario_coverage_test.go (the BDD name-coverage gate).
 
-  @pending  # TestExpandReturnsSummaryBodyFragment
   Scenario: A summarized card expands to the full summary in place
     Given a summarized video in my list
     When I expand its card
     Then the full summary, highlights, and takeaways are returned as an in-place card fragment, not a full page
 
-  @pending  # TestCollapseReturnsCompactCard
   Scenario: An expanded card collapses back to the compact card
     Given an expanded card
     When I collapse it
     Then the compact card fragment is returned in its place
 
-  @pending  # TestExpandedCardOffersChatDock
   Scenario: The expanded card offers the Q&A dock
     Given chat is enabled
     When a summarized card is expanded
     Then the expanded card includes the deeper-dive chat affordance for that video
 
-  @pending  # TestCompactCardExpandOnlyWhenSummarized
   Scenario: Only a summarized card offers expand
     Given a discovered but not-yet-summarized card
     When the card is rendered
     Then it shows its summarize/queue footer and no expand affordance
 
-  @pending  # TestCompactCardHasNoJSDetailFallback
   Scenario: With JS off the card still reaches the full summary
     Given a summarized card
     When it is rendered
     Then its expand affordance carries an href to the detail page as a no-JS fallback
 
-  @pending  # TestDetailAndExpandShareSummaryBody
   Scenario: The detail page and the expanded card show the same summary
     Given a summarized video
     When I view it on the detail page and as an expanded card