docs: daemon: add documentation to remaining missing parts

[artiepoole]

No description provided.

[Copilot]

Pull request overview

This PR primarily improves project documentation (module-level rustdocs and READMEs) across the daemon and macros crates, and also adjusts Cargo/workspace metadata to support publishing and clearer crate identity.

Changes:

• Add/expand rustdoc module documentation and examples across daemon/src/** and fpgad_macros/src/lib.rs.
• Introduce new READMEs / included docs (e.g., daemon/src/softeners/README.md, fpgad_macros/README.md) and a root PUBLISHING.md.
• Centralize package metadata via [workspace.package] and rename crates/packages (daemon → fpgad, cli → fpgad_cli).

Reviewed changes

Copilot reviewed 22 out of 23 changed files in this pull request and generated 10 comments.

Show a summary per file

File	Description
fpgad_macros/src/lib.rs	Adds crate/docs inclusion and rustdoc for the #[platform] proc-macro.
fpgad_macros/README.md	New README describing macros crate usage.
fpgad_macros/Cargo.toml	Moves metadata to workspace + adds publish-oriented metadata.
daemon/src/system_io.rs	Adds module/function rustdocs and examples for filesystem helpers.
daemon/src/softeners/error.rs	Adds module/enum rustdocs for softener error types.
daemon/src/softeners/README.md	Large new softeners guide, included via softeners.rs.
daemon/src/softeners.rs	Includes the softeners README into rustdoc output.
daemon/src/platforms/universal_components/universal_overlay_handler.rs	Adds module/type/method rustdocs for overlay handling.
daemon/src/platforms/universal_components/universal_fpga.rs	Adds module/type/method rustdocs for FPGA sysfs handling.
daemon/src/platforms/universal_components.rs	Removes README include (module now just exports submodules).
daemon/src/platforms/universal.rs	Adds module/type/method rustdocs for universal platform.
daemon/src/platforms/platform.rs	Adds module/trait/function rustdocs for platform registry/traits.
daemon/src/platforms/README.md	Updates platforms documentation text and references.
daemon/src/platforms.rs	Includes platforms README into rustdoc output.
daemon/src/main.rs	Adds crate-level rustdocs for daemon entrypoint and registration.
daemon/src/error.rs	Adds rustdocs describing FpgadError and DBus mapping.
daemon/src/config.rs	Adds module rustdocs for configuration constants.
daemon/src/comm.rs	Adds module rustdocs for comms/DBus structure.
daemon/Cargo.toml	Renames package to fpgad, moves metadata to workspace, updates dependency spec.
cli/Cargo.toml	Renames package/bin to fpgad_cli, moves metadata to workspace.
PUBLISHING.md	New publishing guide and process notes.
Cargo.toml	Adds [workspace.package] shared metadata.
Cargo.lock	Updates lockfile for crate/package renames.

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[Copilot]

Pull request overview

Copilot reviewed 22 out of 23 changed files in this pull request and generated 10 comments.

---

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[artiepoole]

I previously accidentally added some cargo.toml and project name changes into this PR, these have been pushed to #158 which prepares for publishing - the final PR in this chain before dfx-mgr changes.

This was previously causing snap builds to fail with "bin/daemon doesn't exist". Should be fixed 🤞