feat: SDK update for version 8.1.0

[ChiragAgg5k]

This PR contains updates to the SDK for version 8.1.0.

What's Changed

• Added: optional state parameter on createOAuth2Token, returned unchanged on the success and failure URLs

This is a patch on top of the previous stable release: it adds only the state parameter from appwrite/appwrite#14157, plus the version bump and changelog. Generated by diffing the sdk-generator output for the specs before and after #14157.

[hansi-codes]

🔵 Tier A · Mergeable after minor fixes

State values containing reserved query characters are not transmitted unchanged.

Adds an optional state argument to CreateOAuth2Token and includes it in the OAuth request. Updates package metadata, SDK headers, installation instructions, the changelog, and the example for version 8.1.0.

Verdict	New comments	Fixed	Still open
✅ Approved	1	0	0

	Finding	Where
🟡	Encode state as a query parameter value	Appwrite/Services/Account.cs:1943

Fix with agent prompt

### Issue 1
Appwrite/Services/Account.cs:1943
**Encode state as a query parameter value**

This goes through `Client.PrepareRequest` and `Extensions.ToQueryString`, which escapes the assembled URI rather than individual values, leaving `+`, `&`, and `#` unescaped. A state such as `a+b` (common with base64 tokens) arrives as `a b`, while `a&b` is split into parameters, so it cannot be returned unchanged; encode query values individually before assembling the URL.

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For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

📂 Walkthrough · 6

File	Change
Appwrite/Appwrite.csproj	Bumps the package version to 8.1.0.
Appwrite/Client.cs	Updates user-agent and SDK version headers.
Appwrite/Services/Account.cs	Adds the optional OAuth state argument and request parameter.
CHANGELOG.md	Documents the new state parameter in the 8.1.0 entry.
README.md	Updates installation commands to version 8.1.0.
docs/examples/account/create-o-auth-2-token.md	Demonstrates passing the optional state argument.

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_{Reviewed e5b022d · Details · Comment @hansi-codes review to re-run, or mention @hansi-codes with a question.}

[hansi-codes]

🔵 Tier A · Looks good to merge. Summary

[hansi-codes]

Encode state as a query parameter value

This goes through Client.PrepareRequest and Extensions.ToQueryString, which escapes the assembled URI rather than individual values, leaving +, &, and # unescaped. A state such as a+b (common with base64 tokens) arrives as a b, while a&b is split into parameters, so it cannot be returned unchanged; encode query values individually before assembling the URL.

Prompt To Fix With AI

This is a comment left during a code review.
Path: Appwrite/Services/Account.cs
Line: 1943

Comment:
**Encode state as a query parameter value**

This goes through `Client.PrepareRequest` and `Extensions.ToQueryString`, which escapes the assembled URI rather than individual values, leaving `+`, `&`, and `#` unescaped. A state such as `a+b` (common with base64 tokens) arrives as `a b`, while `a&b` is split into parameters, so it cannot be returned unchanged; encode query values individually before assembling the URL.

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

_{🟡 Minor · bug · Reply if this doesn't apply.}