feat: consume PliegoRS topology and prepare RC.3

[terrizoaguimor]

What changed

• Add the shared incremental compiler engine and harden release, portability, distribution, browser-output, adapter-coexistence, and external-adoption evidence gates for RC.3.
• Consume the versioned pliegors-product-topology/1 seam from PliegoRS without adding a runtime dependency.
• Add deterministic route-to-island reachability, bundle partitioning, safe physical IDs, and portable alias validation.
• Pin the coordinated PliegoRS producer at abb8653e75da4a5cb4dd9b51200114fbb1e760c7 from feat: expose optional PliegoCSS product topology pliegors#48.
• Record the exact-head two-process development-loop replay and update its documented latency.

Contract and compatibility

The PliegoRS seam is opt-in and source-pinned because it is not present in the currently published pliego-ssg 0.4.0-beta.1. Existing standalone PliegoCSS input remains supported. Generated bundle planning is deterministic; Style remains an ordinary CSS class at runtime, and PliegoRS does not link PliegoCSS crates.

This branch also contains the coordinated RC.3 baseline and verification architecture accumulated since main; it does not publish RC.3. G7 remains blocked until real external adoption evidence exists.

Evidence

• Focused source, topology, reachability, portability, release-contract, docs, guide, framework, and browser integration tests pass.
• Hosted CI passes on exact head 71d5231daf7c68aadea4a0c96e33f85edb6272d1: https://github.com/celiumsai/pliegocss/actions/runs/33123171128
• Browser/output matrix passes: https://github.com/celiumsai/pliegocss/actions/runs/33123171150
• Adapter coexistence and pinned PliegoRS browser replay pass: https://github.com/celiumsai/pliegocss/actions/runs/33123171124
• Repository distribution passes: https://github.com/celiumsai/pliegocss/actions/runs/33123171163
• CodeQL passes on the exact head: https://github.com/celiumsai/pliegocss/actions/runs/33123203883
• Exact-head integration:pliegors-dev --record-evidence passes with 20 edits, diagnostic failure, recovery, and no-op checks.
• Documentation, CLI help, examples, generated artifacts, and evidence were updated.
• No credentials, private data, or unauthorized media were added.
• Compatibility, performance, security, and size impact were reviewed.

Screenshots or artifacts

Serialized local evidence: docs/benchmarks/data/pliegors-dev-loop.local.json.

No tag, release, crate publication, npm publication, or draft release creation is part of this PR.