feat(AGENT-25): add [scan] include/exclude path filters

[limaronaldo]

Summary

Implements AGENT-25: [scan] include and [scan] exclude glob filters in .agentshield.toml, relative to the scan root. exclude wins when both match. The filter runs before source-file collection/parsing across all adapters (MCP, OpenClaw, Hermes, CrewAI, LangChain, GPT Actions, Cursor Rules) and is surfaced in scan --explain as Path filters.

Two commits:

1. feat(AGENT-25) — the feature: config parsing, glob compilation, precedence (included && !excluded), per-adapter filtering, and --explain visibility. Docs (README.md, AGENTS.md) and the local Huly skill reference. Adds tests/path_filters.rs (include-only, exclude-only, exclude-wins precedence, explain visibility).
2. fix(AGENT-25) — closes a bypass found in code review (see below).

Code review fix (metadata-derived findings)

Review found the first commit filtered parsed source files but not metadata read directly from the scan root, so excluded files still produced findings — violating the acceptance criterion "Excluded files do not produce findings".

Reproduced before the fix:

• exclude = ["package.json"] still emitted SHIELD-009 / SHIELD-012 located at package.json
• exclude = ["tools.json"] still emitted SHIELD-008 from excluded tool metadata

Fix threads ScanPathFilter into the MCP tools.json load path and into the shared parse_dependencies / parse_provenance helpers (used by all adapters), gating every root-relative metadata file on allows_path: requirements.txt, Pipfile.lock, poetry.lock, uv.lock, package.json, package-lock.json, pyproject.toml, tools.json.

Added regression tests for exclude = ["package.json"], ["requirements.txt"], and ["tools.json"] — these failed before the fix (RED) and pass after (GREEN).

Test plan

• cargo test — 253 passed
• cargo test --all-features — 328 passed
• cargo test --no-default-features — 247 passed
• cargo clippy --all-targets --all-features -- -D warnings — no issues
• cargo fmt --all -- --check — clean
• git diff --check — clean
• Manual repro: with exclude active → 0 findings; without exclude → findings return (detectors intact)

Closes AGENT-25.

[limaronaldo]

Review follow-up for AGENT-25 addressed on this branch.

Fixed in c1425b6:

• path filters now use explicit case-sensitive glob matching with literal path separators, so *.py no longer crosses directories;
• leading ./ or / patterns normalize relative to the scan root;
• trailing slash patterns such as legacy/ match directory contents;
• glob semantics are covered for **/generated/**, root/nested generated directories, and case-sensitivity;
• README and starter config comments now document the expected semantics.

Fixed in 8fd6784:

• metadata path-filter regression tests now assert absence of supply-chain findings, not only absence of one manifest location, so the previous SHIELD-012 migration/vacuous-test gap is covered.

Local verification passed:

• cargo fmt --all -- --check
• cargo test (258 tests)
• cargo clippy --all-targets --all-features -- -D warnings
• cargo test --no-default-features
• cargo clippy --all-targets --no-default-features -- -D warnings
• CLI smoke with exclude = ["legacy/"] confirmed the excluded file and SHIELD-001 do not appear in JSON output.