docs: rewrite changelog for the 1.0.0 release

[andrew-bekhiet-solid]

Motivation

0.1.1 is the last version actually published to pub.dev — 1.0.0 was never released, so the pending 1.0.1 section described changes that no user has ever received. This merges both into a single 1.0.0 entry so the changelog reflects what an upgrading user will actually experience, and prepares the package for release.

Corrections to previously documented entries

Entry	Problem
Service renames	Named classes that never existed (DebounceLanguageToolService, ThrottleLanguageToolService). Real renames: LangToolService → LanguageToolService, DebounceLangToolService → DebounceLanguageCheckService, ThrottlingLangToolService → ThrottlingLanguageCheckService. The LangToolService rename was missing entirely.
key in the added-properties list	The constructor already accepted super.key in 0.1.1 — never added.
autofocus in the same list	Only appears "new" due to the case change; it's the autoFocus rename, already covered by its own breaking entry.
PR #99 (remove duplicate super.key)	Net-zero: the duplication was introduced and removed within PR #95's own branch history. Dropped.
PR #98 (example build files)	Example app only, no lib/ changes. Dropped.

Newly documented changes

These were missing from the changelog altogether:

• LanguageToolTextField now extends TextField instead of StatefulWidget (feat: add missing text field properties #90) — the architectural change underpinning the whole property list
• onTextChange → onChanged, onTextSubmitted → onSubmitted (feat: add missing text field properties #90) — breaking, previously undocumented
• LanguageCheckService now requires a language getter/setter (feat: allow overriding languageCheckService #93) — breaking for anyone implementing the interface
• Dark-mode mistake popup fix (Fix Mistake Popup visibility on dark mode #82 #88)
• recheckText(), Result export, FilteredLanguageCheckService, the throttling offset filter (feat: support adding words to dictionary with a callback #95)
• The fix: recheck text on changing language #96 / fix: clear mistakes that fall out of new text range #97 / fix bug in LanguageToolTextField._textControllerListener #100 fixes

[gemini-code-assist]

Caution

The consumer version of Gemini Code Assist on GitHub has been sunset. All code review activity has officially ceased.

[solid-danylosafonov]

LGTM!