heph.nvim: task views — next/list/capture/attention/state/log (slice 11b)

Backend: enrich `list` to return titled RankedTask rows (title +
canonical_context_id, via a shared ranked_from_row with `next`), so the
Organizational view needs no N+1 node.get. TDD: query_surface test asserts
list rows carry title + context id.

Plugin:
- view.lua: Tactical `next` + Organizational `list` rendered scratch buffers;
  <CR> opens the row's canonical-context doc. Narrowed the node autocmd to
  heph://node/* so view buffers (heph://next, heph://list) don't trip it.
- task.lua: capture, set-attention, done/drop, skip, per-task log append, all
  resolving "the current task" from the buffer (a task node, or a context doc
  via its canonical-context backlink).
- picker.lua: vim.ui.select with Telescope auto-upgrade (headless-safe).
- command.lua: :Heph next/list/capture/attention/done/drop/skip/log/search.

e2e: capture→next→open context→add/check checklist→done; recurring
fresh-checklist (complete rolls forward in place, next occurrence all-unchecked
— the §4.4 hard requirement). 6 specs green via `mise run test-nvim`.

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

heph.nvim/lua/heph/picker.lua

@@ -0,0 +1,56 @@
+--- A single selection primitive. Uses built-in `vim.ui.select` so headless e2e
+--- needs no plugins; auto-upgrades to Telescope when it is installed and not
+--- explicitly disabled. Tests set `vim.g.heph_force_ui_select` and stub
+--- `vim.ui.select`, so a picker never blocks in `--headless`.
+
+local M = {}
+
+local function telescope_available()
+  return pcall(require, "telescope")
+end
+
+--- Select one of `items`. `opts.prompt`, `opts.format(item)->string`.
+--- `on_choice(item|nil, index|nil)` — nil when cancelled.
+function M.select(items, opts, on_choice)
+  opts = opts or {}
+  if not vim.g.heph_force_ui_select and telescope_available() then
+    -- Telescope path: a thin wrapper so fuzzy UX is available when present.
+    -- (The dropdown is intentionally minimal; richer pickers can come later.)
+    local pickers = require("telescope.pickers")
+    local finders = require("telescope.finders")
+    local conf = require("telescope.config").values
+    local actions = require("telescope.actions")
+    local action_state = require("telescope.actions.state")
+    pickers
+      .new({}, {
+        prompt_title = opts.prompt or "heph",
+        finder = finders.new_table({
+          results = items,
+          entry_maker = function(item)
+            local display = opts.format and opts.format(item) or tostring(item)
+            return { value = item, display = display, ordinal = display }
+          end,
+        }),
+        sorter = conf.generic_sorter({}),
+        attach_mappings = function(bufnr)
+          actions.select_default:replace(function()
+            actions.close(bufnr)
+            local sel = action_state.get_selected_entry()
+            on_choice(sel and sel.value or nil)
+          end)
+          return true
+        end,
+      })
+      :find()
+    return
+  end
+
+  vim.ui.select(items, {
+    prompt = opts.prompt,
+    format_item = opts.format,
+  }, function(choice, idx)
+    on_choice(choice, idx)
+  end)
+end
+
+return M