feat(input): add persistent input history

[UncleBill]

Plain input dialogs (e.g. workspace.rename, requestInput) now keep a
persistent input history, like Vim's built-in input() history:

• Inputs confirmed with <cr> are saved to the input_history file
  under the coc data home (~/.config/coc/input_history by default),
  reusing the existing Mru class (same storage as the commands
  history): newest first, deduplicated on recall, capped at 100 entries.
  Cancelled (<esc>) and single-character inputs are not saved.
• <up> recalls the previous accepted input, <down> moves to the more
  recent one; moving past the newest entry restores the text typed
  before navigation. The cursor is clamped at both ends (no wrap).

Behavior notes:

• Neovim: in non-list input dialogs <up>/<down> previously moved
  the cursor within the single line; they now navigate the history.
  C-p/C-n are deliberately not bound to avoid conflicting with
  insert-mode completion.
• QuickPick (list) mode is unchanged: <up>/<down> still navigate
  the filtered list; the history is only recalled in plain input
  dialogs.
• Vim8 needs no new navigation code: bin/prompt.js already
  forwards <up>/<down> through the existing PromptKeyPress
  channel, previously only consumed by QuickPick. The recalled value is
  rendered through the existing programmatic value update
  (coc#dialog#change_input_value).
• No public API, typings, or configuration changes.

Tested on both lanes (node scripts/test/cli.mjs): history navigation
and persistence on Neovim, QuickPick list navigation regression, and
Vim8 recall incl. confirming a recalled entry with a placeholder
active.

🤖 Generated with Claude Code

[codecov]

Codecov Report

❌ Patch coverage is 89.79592% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 98.14%. Comparing base (44e2547) to head (9253d23).

Files with missing lines	Patch %	Lines
src/model/input.ts	89.79%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5775      +/-   ##
==========================================
- Coverage   98.15%   98.14%   -0.01%     
==========================================
  Files         306      306              
  Lines       53074    53123      +49     
  Branches     9366     9380      +14     
==========================================
+ Hits        52094    52138      +44     
- Misses        847      852       +5     
  Partials      133      133              

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