feat(tui): restyle the ADR split and import overlays (#144)

[aksOps]

Slice 5 of the map #136 cut (spec section 9.3): the ADR split review flow and
the forge import flow move onto internal/tui/theme and internal/tui/widget.
The binding spec is docs/design/tui-design-spec.md on design/tui-spec.

This slice also takes the two overlay-adjacent leftovers the merged slices
recorded and handed forward: the section 4 step 1 backdrop dim (PR #147
deviation 1, PR #149 deviation 6) and pointer.go's raw reverse-video escape
(PR #149 deviation 8).

Closes #144.

What the spec dictated

Section 4 - elevation. Both NewStyle().Border(RoundedBorder()) frames
(spec section 9.1 names them) are gone. Each overlay is a widget.Overlay
panel: a solid Brand header band carrying the title, an OverlaySurf body,
OverlayBand section breaks (SOURCE, STORIES, ISSUES), an OverlayBand
footer band carrying the hints with the ADR split's scroll indicator
right-aligned, and the two Shadow bands cast one cell down and right through
widget.OverlayLayers. Geometry and the per-overlay width caps come from
theme.Metrics.Overlay (ADRSplit 100, IssueImport 88); the two dead
literals are gone.

Section 4 step 1 - the dim, finally wired. Model.backdrop() returns the
model the board renders through: with any overlay open it is the same model
carrying styles.Dimmed, so renderBoard re-renders the whole board through
the second built palette. It is not a post-pass over a rendered string, which
is what the spec forbids, and it is one call at the compose site because #148
made the board renderer take styles.

Section 9.1 - the pressed token. pointer.State.Render takes a
*theme.Styles and delegates to the new Styles.PressedRun. The theme owns
the attribute and the re-arming a composed run needs; the pointer package only
decides which control wears it. The run still closes by clearing the attribute
alone rather than resetting the style, because callers substitute it into the
middle of a styled line (help.go, settings_view.go).

Sections 6.2 and 9.2 - the seam. adrsplit/view.go and
issueimport/view.go leave the seam allowlist; the list is down to one
entry (help.go) and its size cap with it. Both overlays take a
*theme.Styles through SetStyles, threaded from internal/tui/model.go on
construction and on tea.BackgroundColorMsg, and neither constructs a style.

Section 5.1 - kb widgets. Actions are widget.Button, the include and
proposal marks are widget.Check, the ADR split's scroll position is
widget.ScrollHint, and every body row goes through widget.OverlayRow or
widget.Section.

Section 5.2 - charm, where the spec assigns it. huh's inline Select
renders the Source, Max stories, Priority, Effort and Destination choices;
huh's Note renders the two AI disclaimer blocks in adrsplit. The bubbles
spinner replaces the static ... on every busy state in both overlays
(reading the file, splitting, creating card i of N, fetching and drafting), and
the bubbles progress bar renders issueimport's writing i/N. The huh
adapters moved from internal/tui to internal/tui/formview because three
packages now render them; formview.HuhInlineSelect is the new one.

Section 6.4 - goldens. TestADRSplitInputGolden is regenerated and now
pins theme.StructureProfile explicitly. Three goldens are new:
TestADRSplitReviewColorGolden, and the pair spec section 6.4 asks for on the
issue-import overlay, which had none - TestIssueImportGolden (structure) and
TestIssueImportColorGolden (truecolor over a board background, with the write
progress bar in frame).

Interaction is frozen

Every keymap, flow, session-scoping rule and mouse target of v1.0.1 survives.
Three mechanical changes were needed to keep them surviving a themed render:

• Pointer targets are structural. Both overlays used to recover a control
  by line arithmetic over the body (adrsplit.controlRows) or by matching the
  rendered line text (issueimport). Rows now carry their target, and the
  buttons that share a row carry their column offset. Same control ids, same
  rects, same messages - and an ADR or a forge draft title can no longer
  impersonate a control, which is what the two impersonation tests assert.
• A created story keeps its rows and loses its targets. The old line
  arithmetic skipped created stories entirely; the row model blanks their
  targets instead, so neither the tab cycle nor a click can reopen a story that
  is already written.
• Pressed feedback is the token, not a text substitution. [>Discard<] and
  [>Cancel<] are gone; the labels stay [ Discard ] and [ Cancel ] and
  wear reverse video. Two assertions moved from the substituted text to the
  attribute in the composed frame.

Deviations, and why

1. issueimport's max stays a plain field. Spec section 5.2 assigns
   Select to "Max stories"; that is the ADR split's field and it is a choice.
   The import's max accepts digit keys 0-9 as direct entry, which an inline
   Select cannot express, so it keeps its value rendering.
2. huh's Select is used inline, and it still does not receive. The frozen
   layout gives each choice one row and one pointer target; a stacked Select is
   a title plus one row per option. The inline form is the only one that fits.
   As in feat(tui): restyle the editor, settings, and dialogs (#143) #149 the field is built from kb's state, rendered and dropped - huh
   owns focus and its own keymap, and exposes no hit regions.
3. widget.Check replaces [x] include and [ ]. Section 5.1 assigns the
   checklist row to the widget, and these two rows are checklist rows. A
   created or already-written item takes the third mark (CheckDropped), which
   is what "out of the batch" looks like. Three test needles moved with it.
4. The status line moved into the footer band. It was a body row in both
   overlays; the panel has a footer band for exactly that, and it costs each
   overlay one row less. While a status shows it replaces the hint ladder,
   which is the pattern feat(tui): restyle the card detail overlay (#142) #147 and feat(tui): restyle the editor, settings, and dialogs (#143) #149 already ship.
5. The import panel is as tall as its content. Section 4's fixed geometry
   is the card detail pane's. This overlay windows its own proposals
   (reviewWindow, frozen at min(h-10, 12) rows) and has never scrolled a
   panel, so pinning the panel to the frame would have double-limited it. The
   ADR split, which does scroll, takes the fixed min(max(h-2,7), h) geometry
   and gains one body row from losing the border.
6. issueimport's ref field goes through formview.Input. It rendered
   textinput.Model.View() straight into a row whose own truncation maps
   control runes to spaces, so its escapes showed up as visible [37m text.
   Incidental, pre-existing, and fixed here because this is the row's restyle.
7. The spinner tick is batched at the operation start. Two test helpers
   walk the batch and skip the tick. The alternative - ticking for as long as
   the overlay is open - costs a timer on an idle overlay.
8. cardeditor's drafting/saving states keep their static text. Spec
   section 5.2 names them for the spinner too, but they are Restyle the editor, settings, and dialogs #143's surface and
   it has shipped. Left for the map to place.

Dependency

charm.land/bubbles/v2/progress pulls github.com/charmbracelet/harmonica v0.2.0 (MIT, charmbracelet) as an indirect requirement for its spring
animation. The bar itself is rendered with ViewAs, so nothing animates.

Verification

Check	Result
go build ./...	pass
go vet ./...	pass
sh scripts/check-go-coverage.sh	pass, total 96.9% (gate 96.4%)
internal/tui coverage	96.5% (floor 90%)
internal/tui/adrsplit coverage	97.7%
internal/tui/issueimport coverage	99.4%
internal/tui/formview coverage	98.2%
internal/tui/theme, widget, pointer coverage	100.0%
go test -race ./internal/tui/...	pass
sh scripts/check-go-format.sh	clean

[sonarqubecloud]

Quality Gate failed

Failed conditions
3.4% Duplication on New Code (required ≤ 3%)

See analysis details on SonarQube Cloud