fix(inference,tools): unblock llama.cpp tool stages + workspace-relative file_read

Two fixes surfaced by the 2026-06-08 QA audit running role_pipeline on a local
llama-server.

F-001: LlamaCppInferenceProvider sent both a GBNF grammar and tools on the same
request; llama.cpp rejects the combination ("Cannot use custom grammar
constraints with tools"), failing every stage that has tools and produces a
schema-constrained artifact. Drop the grammar when tools are present and rely on
post-hoc schema validation + retry (invariant #7 still holds). TODO left for a
first-class emit_artifact tool as the proper fix.

F-005: FileReadTool resolved relative paths via toAbsolutePath() against the JVM
process cwd instead of the bound workspace, so the file-read jail anchored to the
wrong root and disagreed with the Plane-2 PATH_CONTAINMENT check. Add workingDir
to FileReadConfig, wire workspace.workingDir in the per-workspace tool builder,
and give FileReadTool a resolvePath() mirroring FileWriteTool/FileEditTool.

apps/server/src/main/kotlin/com/correx/apps/server/Main.kt

@@ -555,6 +555,7 @@ private fun buildToolConfigForWorkspace(
     fileRead = FileReadConfig(
         enabled = toolsConfig.fileReadEnabled,
         allowedPaths = workspace.allowedPaths,
+        workingDir = workspace.workingDir,
     ),
     fileWrite = FileWriteConfig(
         enabled = toolsConfig.fileWriteEnabled,