feat: Update documentation with new sections for workspace guide, flags & environment, and troubleshooting map; enhance CLI reference and build/run notes for improved clarity.

docs/reference-and-help/flags-and-environment.md

@@ -0,0 +1,48 @@
+# Flags & environment
+
+This page summarizes runtime flags and environment variables that affect DCR behavior.
+
+## Build/run flags
+
+Used with `dcr build` and `dcr run`:
+
+- `--debug`: select debug profile.
+- `--release`: select release profile.
+- `--force`: ignore incremental cache checks and rebuild.
+- `--clean`: remove `target/<profile>` and `build.clean` paths before build.
+
+Notes:
+
+- Flags can be passed in any order.
+- Duplicate profile flags are rejected.
+
+## Clean flags
+
+Used with `dcr clean`:
+
+- `--debug` / `--release`: clean only selected profile directory.
+- `--all`: in workspace root, also clean all members.
+
+## Environment variables
+
+Tool selection overrides:
+
+- `DCR_COMPILER` (all languages)
+- `DCR_CC`, `DCR_CXX`, `DCR_AS`, `DCR_AR`, `DCR_LD`
+
+Diagnostics:
+
+- `DCR_DEBUG=1` enables verbose build logging.
+
+## Quick examples
+
+```sh
+# Force full release rebuild
+dcr build --release --force
+
+# Clean before debug run
+dcr run --clean --debug
+
+# Use custom compiler from env
+DCR_CC=clang-18 dcr build --debug
+```