[Sunrisepeak]

Dependency-owned executables and shared libraries currently lose their Windows resources when built through a consumer. Repeated planning also rewrites unchanged lockfiles, and build-database output reports synthesized host files as watch inputs, creating a watcher feedback loop.

This change binds resources to the image's package, preserves unchanged lockfiles and reports I/O errors, and excludes generated host inputs while retaining editable build dependencies. It updates the specifications and both user-documentation trees and prepares release 2026.10.21.1 without advancing the bootstrap pin.

Closes #826
Closes #807

#816 is resolved as a design-boundary decision: the default text scanner does not expand includes. Visible imports already receive transitive mappings. This PR documents that boundary and adds a supported-path control test; it adds no workaround or compatibility mode. After merge, #816 will be closed explicitly as not planned, without an issue comment.

Implementation checkpoints and dependency order are recorded in .agents/docs/2026-10-21-resource-ownership-module-scan-and-lock-write-design.md. The branch contains checkpoint commits; final merge uses squash as requested.

Validation:

• The final 2026.10.21.1 candidate self-hosts and passes all 149 root unit test targets, including the lockfile and symlink checks.
• E2E 01, 844, 688, 913, 921, 923 and 924 pass locally with the fresh candidate.
• Released-binary controls fail for unchanged-lock mtime, generated host watch entries, and missing dependency DLL resources.
• MinGW resource checks cover EXE/DLL ownership, same-named targets, standalone roots, workspace selection changes, manifest rebuild and target-independent missing-input validation.
• Version pins, module wiring, documentation style/structure, file lengths and schema/deprecation checks pass locally. The records index is verified in a clean checkout.
• All 67 jobs in the final-head cross-platform CI passed: https://github.com/mcpp-community/mcpp/actions/runs/39456970836.
• Independent xlings and mcppls ecosystem canaries passed: https://github.com/mcpp-community/mcpp/actions/runs/39457029515.
• Final review confirmed package ownership, editable-input preservation, lock I/O and file-object semantics, scanner scope, upgrade behavior and the release/bootstrap version boundary. No further source changes were required.
• Local heavy commands are serialized and limited to two CPU cores and 8 GiB of memory.