feat: add GetClientLibraryPath() to FirebirdEnvironment

Exposes the Firebird client library path as a method on FirebirdEnvironment,
following the same GetXxxPath() convention as GetServerPath(), GetIsqlPath(), etc.

- Windows: returns fbclient.dll in the environment root
- Linux: returns the versioned libfbclient.so.X (e.g. libfbclient.so.5),
  falling back to the unversioned libfbclient.so symlink

Callers that need to supply an explicit library path to a Firebird client
driver (e.g. python3-firebird-driver, firebird-driver .NET) can now use:
  \.GetClientLibraryPath()
instead of writing OS-conditional path logic themselves.

Add integration test to FirebirdEnvironment.Tests.ps1 verifying that the
returned path exists and matches the expected filename pattern.

Author: fdcastel

Tests/FirebirdEnvironment.Tests.ps1

@@ -68,4 +68,18 @@ Describe 'FirebirdEnvironment' -Tag 'Integration' {
         New-FirebirdEnvironment @FirebirdEnvParams -Path $TestEnvironmentPath @FirebirdExtraParams | Out-Null
         $LASTEXITCODE | Should -Be 0
     }
+
+    It 'GetClientLibraryPath returns the client library file' {
+        $fbEnv = New-FirebirdEnvironment @FirebirdEnvParams -Path $TestEnvironmentPath @FirebirdExtraParams
+
+        $clientLib = $fbEnv.GetClientLibraryPath()
+
+        $clientLib | Should -Not -BeNullOrEmpty
+        $clientLib | Should -Exist
+        if ($IsWindows) {
+            $clientLib.Path | Should -Match 'fbclient\.dll$'
+        } else {
+            $clientLib.Path | Should -Match 'libfbclient\.so'
+        }
+    }
 }

Types/FirebirdEnvironment.ps1

@@ -55,6 +55,23 @@ class FirebirdEnvironment {
         return $this.GetFirebirdToolPath('nbackup')
     }
 
+    # Return the client library path (fbclient.dll on Windows, libfbclient.so.X on Linux)
+    [System.Management.Automation.PathInfo] GetClientLibraryPath() {
+        if ($global:IsWindows) {
+            return Resolve-Path (Join-Path $this.Path 'fbclient.dll')
+        }
+        # Prefer the versioned .so.X form (e.g. libfbclient.so.5); fall back to the
+        # unversioned symlink if no versioned file is found.
+        $libDir = Join-Path $this.Path 'lib'
+        $versioned = Get-ChildItem -Path $libDir -Filter 'libfbclient.so.*' -ErrorAction SilentlyContinue |
+            Where-Object { $_.Name -match '\.so\.\d+$' } |
+            Select-Object -First 1
+        if ($versioned) {
+            return Resolve-Path $versioned.FullName
+        }
+        return Resolve-Path (Join-Path $libDir 'libfbclient.so')
+    }
+
     # Private helper to get tool path
     hidden [System.Management.Automation.PathInfo] GetFirebirdToolPath([string]$tool) {
         $toolPath = if ($global:IsWindows) {