fix(macros): resolve quick start source info from item spans

[eboody]

Fixes #17.

Summary

• prefer annotated item spans over anonymous proc-macro call sites when resolving source and module information for #[state], #[machine], #[transition], and #[validators]
• reject non-disk span files before attempting source scans and keep the call-site path only as a fallback
• add a Quick Start regression fixture and switch docs/inspector-plan.md to repo-relative links so the docs link check passes under act

Testing

• cargo test --workspace
• act -j stable
• act -j msrv-1-93
• act -j security-deny
• act -j security-audit
• act -j nightly-canary

[Copilot]

Pull request overview

This PR fixes Quick Start failures (Issue #17) by improving how the statum-macros proc-macros resolve source file + module path information, preferring annotated item spans over proc-macro call-site spans and avoiding non-disk paths during source scans.

Changes:

• Add span-based source/module resolution helpers in macro_registry and switch #[state], #[machine], #[transition], and #[validators] to use them.
• Improve validator machine resolution diagnostics by using span-derived source info (with call-site fallback) for source scanning.
• Add a Quick Start regression UI fixture and update docs to use repo-relative links so link checking works under act.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
statum-macros/tests/ui/valid_quick_start.rs	Adds a Quick Start regression fixture exercising #[state], #[machine], and #[transition].
statum-macros/tests/macro_errors.rs	Registers the new Quick Start UI test as a passing trybuild case.
statum-macros/src/validators/resolution.rs	Uses span-derived source info to improve candidate scanning/diagnostics during validator machine resolution.
statum-macros/src/validators.rs	Adjusts parse_validators to accept a parsed ItemImpl (caller parses once).
statum-macros/src/state.rs	Switches #[state] enum metadata/module resolution to span-based helpers.
statum-macros/src/machine/metadata.rs	Switches #[machine] struct metadata/module resolution to span-based helpers.
statum-macros/src/lib.rs	Uses impl-item spans for resolving module path in #[transition] / #[validators], and parses ItemImpl once for validators.
macro_registry/src/callsite.rs	Introduces span-based (file,line) and module-path helpers, rejecting non-disk paths before scanning.
macro_registry/Cargo.toml	Adds proc-macro2 with span-locations to support span-based resolution.
docs/inspector-plan.md	Replaces absolute local-file links with repo-relative links for CI doc link checks.

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[Copilot]

line_number for #[validators] is now taken from item_impl.impl_token.span.start().line, which can be 0 when span location info is unavailable. That value is later used to derive stable hashed identifiers (and potentially in diagnostics), so a 0 can increase the chance of identifier collisions and reduce error-message quality. Consider deriving the line number via macro_registry::callsite::source_info_for_span_or_callsite(item_impl.impl_token.span) (or falling back to Span::call_site().start().line when 0).

Suggested change

	let line_number = item_impl.impl_token.span.start().line;
	let mut line_number = item_impl.impl_token.span.start().line;
	if line_number == 0 {
	line_number = Span::call_site().start().line;
	}

[eboody]

Fixed in 3b71577. #[validators] now derives line_number from source_info_for_span_or_callsite(span) and only falls back to the raw span line when needed.