docs: polish from #271 review (PR-link placeholder + NullLoggerFactory.Instance)

AGENTS.md

@@ -201,7 +201,7 @@ Anti-pattern: don't keep flipping the code on the same style point. Flip the rul
 
 ## Communicating with the User
 
-- **Reference every pull request as a clickable link.** When you mention a PR - in chat, a summary, or a report - render it as a markdown link to the PR (`[#123](https://github.com/<owner>/<repo>/pull/123)`), never a bare `#123`. The same applies to issues and commits.
+- **Reference every pull request as a clickable link.** When you mention a PR - in chat, a summary, or a report - render it as a markdown link to the PR (`[#123](https://github.com/OWNER/REPO/pull/123)`), never a bare `#123`. The same applies to issues and commits.
 - **Ask for input as a numbered list.** When you need the user to decide or answer, present the questions - and any options - as a numbered list so they can reply per number. A single inline question is fine; two or more are always numbered.
 
 ## Workflow YAML Conventions

CODESTYLE.md

@@ -251,7 +251,7 @@ Follow the scope hierarchy in [Analyzer Diagnostics and Suppressions][analyzer-d
    logger.LogError(exception, "{Function}", function);
    ```
 
-2. **Libraries log through abstractions, never a concrete backend.** A NuGet **library** depends only on `Microsoft.Extensions.Logging.Abstractions` and exposes an `ILoggerFactory` seam - a settable global factory defaulting to `NullLoggerFactory` (fallback `NullLogger.Instance`) with `SetFactory`/`TrySetFactory`, and/or an `ILoggerFactory`/`ILogger` parameter in its API. It must **not** reference Serilog or any sink - that forces a logging framework on every consumer and drags in AOT-incompatible dependencies. The consuming **application** owns the concrete logger (Serilog is fine there), bridges it to `ILoggerFactory` (e.g. `SerilogLoggerFactory` from `Serilog.Extensions.Logging`), and injects it. Reference: `LanguageTags` - `LogOptions` in the library; the CLI's `LoggerFactory` builds the Serilog-backed factory and injects it via `LogOptions.SetFactory`.
+2. **Libraries log through abstractions, never a concrete backend.** A NuGet **library** depends only on `Microsoft.Extensions.Logging.Abstractions` and exposes an `ILoggerFactory` seam - a settable global factory defaulting to `NullLoggerFactory.Instance` (fallback `NullLogger.Instance`) with `SetFactory`/`TrySetFactory`, and/or an `ILoggerFactory`/`ILogger` parameter in its API. It must **not** reference Serilog or any sink - that forces a logging framework on every consumer and drags in AOT-incompatible dependencies. The consuming **application** owns the concrete logger (Serilog is fine there), bridges it to `ILoggerFactory` (e.g. `SerilogLoggerFactory` from `Serilog.Extensions.Logging`), and injects it. Reference: `LanguageTags` - `LogOptions` in the library; the CLI's `LoggerFactory` builds the Serilog-backed factory and injects it via `LogOptions.SetFactory`.
 
 3. **CallerMemberName**: Use for automatic function name tracking