parity(1): vimwiki per-wiki config keys, table colspan/rowspan,

named link commands, mouse maps

Parity audit Cluster 1 — small wins.

WikiConfig (server) extended with 14 vimwiki globals:
- `index` (`g:vimwiki_index`), wired into `:VimwikiIndex` so users
  with a custom index page stem (e.g. `home`) get the right file.
- `diary_frequency`, `diary_start_week_day`, `diary_caption_level`,
  `diary_sort`, `diary_header` — diary keys (weekly/monthly/yearly
  semantics land in Cluster 4; the keys parse now so config
  migration doesn't need to wait).
- `maxhi`, `listsyms`, `listsyms_propagate`, `list_margin`,
  `links_space_char`, `nested_syntaxes`, `auto_toc` — list +
  highlight knobs the renderer/handlers can consult.

All keys threaded through `RawWiki` → `WikiConfig::from(RawWiki)`,
defaults centralised in `wiki_defaults()` so `empty()`, `from_root()`,
the legacy single-wiki path, and the `RawWiki` impl stay in sync.

Lua front-door (`lua/nuwiki/config.lua`) now documents the multi-wiki
`wikis = {…}` shape with every accepted per-wiki key — users who
prefer Lua tables no longer have to round-trip through
`init_options` raw JSON.

HTML renderer (`crates/nuwiki-core/src/render/html.rs`):
- New `table_spans()` pre-pass resolves vimwiki's `>` (col_span) and
  `\\/` (row_span) continuation markers into proper HTML
  `colspan="N"` / `rowspan="N"` attributes on the lead cell. Continuation
  cells emit nothing, matching what browsers expect.
- The old behaviour (emitting `class="col-span"` / `class="row-span"`
  as visual markers) is gone — replaced with real merging so the
  rendered HTML matches the source semantics.

Named ex-commands:
- `:VimwikiNextLink` / `:VimwikiPrevLink` — were keymapped only
  (`<Tab>`/`<S-Tab>`); now have explicit `:` commands in both editor
  paths, dispatching to new `nuwiki.commands.link_next` / `link_prev`
  pure-Vim/Lua helpers.
- `:VimwikiBaddLink` — adds the link target's file to the buffer
  list without switching focus. Goes through
  `textDocument/definition` and runs `:badd <fname>` on the resolved
  URI.

Mouse maps (opt-in via `mappings.mouse = true` in Lua or
`g:nuwiki_mouse_mappings = 1` in Vim):
- `<2-LeftMouse>` follows, `<S-2-LeftMouse>` / `<C-2-LeftMouse>`
  follow in split/vsplit, `<MiddleMouse>` adds to buflist,
  `<RightMouse>` goes back. Mirrors upstream vimwiki's defaults.

Tests: 7 new in `parity_cluster_1.rs` covering the per-wiki config
defaults + raw JSON parse, the legacy-single-wiki path, colspan
folding into a lead cell with no leftover class markers, rowspan
across rows, no-attrs when the table has no spans, and a sanity
paragraph render. Total 421 Rust tests pass; clippy clean; both
keymap harnesses still green (20 nvim + 12 vim).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

lua/nuwiki/config.lua

@@ -6,11 +6,31 @@
 local M = {}
 
 M.defaults = {
+  -- v1.0 single-wiki shorthand. The server desugars these into a
+  -- one-entry `wikis = {…}` list. Use either this or the multi-wiki
+  -- form below; if both are set, `wikis` wins.
   wiki_root      = '~/vimwiki',
   file_extension = '.wiki',
   syntax         = 'vimwiki',
   log_level      = 'warn',
 
+  -- v1.1 multi-wiki shape. Each entry honours every per-wiki key the
+  -- server understands. Leave nil to fall through to the shorthand
+  -- above.
+  --
+  -- Per-wiki keys (all optional, server defaults documented in SPEC
+  -- §12.11):
+  --   name, root, file_extension, syntax, index
+  --   diary_rel_path, diary_index, diary_frequency,
+  --   diary_start_week_day, diary_caption_level, diary_sort,
+  --   diary_header
+  --   html_path, template_path, template_default, template_ext,
+  --   template_date_format, css_name, auto_export, auto_toc,
+  --   html_filename_parameterization, exclude_files, color_dic
+  --   maxhi, listsyms, listsyms_propagate, list_margin,
+  --   links_space_char, nested_syntaxes
+  wikis = nil,
+
   -- Phase 19: per-buffer glue. Each subgroup mirrors vimwiki's
   -- `g:vimwiki_key_mappings` shape and can be flipped off
   -- independently to suppress that group of keymaps.
@@ -23,7 +43,8 @@ M.defaults = {
     table_editing = true,  -- gqq, gq1, gww, gw1, <A-Left>, <A-Right>
     diary         = true,  -- <C-Down>, <C-Up>
     html_export   = true,  -- <Leader>wh, <Leader>whh
-    text_objects  = true,  -- ah, ih, …
+    text_objects  = true,  -- ah, ih, aH, iH, al, il, a\, i\, ac, ic
+    mouse         = false, -- <2-LeftMouse>, <RightMouse>, …  (opt-in)
   },
 
   -- Phase 19: folding. `'lsp'` uses the server's `foldingRange`