[roll] Roll fuchsia [beads][planter] Add 10 machinery lessons

Machinery updates planter learned from migration reviews. Each lesson
in lessons/ explains the root cause and why it is a general rule:

- 2026-10-02-bazel-visibility-scoping-of-exports-files-and.md: Bazel
  visibility scoping of exports files() and migration commit-message
  conventions
- 2026-10-02-commit-message-accuracy-conflating-bazel-target.md: Commit
  message accuracy: conflating Bazel target names with Rust crate name /
  macro-generated target names
- 2026-10-02-commit-message-check-derives-the-migrated.md: Commit
  message check derives the migrated directory without the layout
  relocation rules (GN secondary overlay tree) and requires a migration
  subject for blocked changes that migrate nothing
- 2026-10-02-commit-message-test-footer-and-test-wiring.md: Commit
  message Test: footer and test wiring: migrated tests must be reachable
  from (and verified through) the ancestor Bazel test suite()
  aggregating the area's tests
- 2026-10-02-dual-build-test-handling-hand-written-gn-test.md:
  Dual-build test handling: hand-written GN test templates (rustc
  test/go test) above the BAZEL2GN SENTINEL treated as
  bazel2gn-convertible targets
- 2026-10-02-migration-commit-message-accuracy-undisclosed.md: Migration
  commit message accuracy: undisclosed shared build-rule changes and
  naming internal rules instead of the macros and targets the
  BUILD.bazel file actually defines
- 2026-10-02-migration-commit-message-conventions-subsystem-tag.md:
  Migration commit message conventions: subsystem tag selection
  (including no-parent-subsystem case) and Bazel Test: footer command
  form/ordering
- 2026-10-02-rust-unit-test-data-dependencies-test-only-files.md: Rust
  unit-test data dependencies: test-only files must use test data (or
  host test data), not the runtime data attribute
- 2026-10-02-test-export-reachability-through-bazel-test-suite.md: Test
  export reachability through Bazel test suite aggregation across
  packages (exporting a test via another package's test suite that a GN
  bazel test suite lists)
- 2026-10-02-third-party-code-built-through-gn-s-secondary.md:
  Third-party code built through GN's secondary source tree
  (build/secondary overlay) migrated in place instead of to the //third
  party/<name>/src layout

NO_IFTTT=planter machinery quotes LINT.IfChange blocks as examples

Test: None, planter machinery (prompts and checks), not in build.
Original-Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1863495
Original-Original-Revision: 8be8526182c10ca8651e5e1a56691e631cffbbed
GitOrigin-RevId: ce530a1f238da27d34e8ea38f2130c3b42644f1b
Change-Id: Id271cf08593729c937bf183ecfedd0ba26ac7ecc
Reviewed-on: https://fuchsia-review.googlesource.com/c/integration/+/1863179
Cr-Commit-Position: refs/heads/main@{#204056}