views: highlight all occurrences of the token under the cursor

Editor-style highlight-all: whenever the cursor lands on an identifier, every
other occurrence of that same whole-word token is highlighted across the visible
listing AND the decompiler view (IDA's identifier-highlight behaviour).

* new _word_occurrences() finds whole-word spans in a line (reuses the same
  char==cell alignment search already relies on).
* ColumnCursor gains _hl_word + _refresh_hl(): after any cursor move (h/l, w/b,
  0/eol, j/k, mouse click, search jump) it recomputes the token under the cursor
  and repaints the viewport only when it changed. Tokens must be >=2 chars and
  start with a letter/underscore.
* ListingView.render_line and DecompView.render_line overlay every occurrence
  with the existing _S_WORD background; the block cursor still marks the current.

Verified: cursor on 'rbp' highlights 5 visible listing rows; cursor on 'v23'
highlights it across the decompiler; mouse/disasm_nav/decomp_nav/listing_view/
func_banners/follow_xrefs/continuous_view/decomp_follow_self 42/0.

0 files changed, 0 insertions, 0 deletions