docs(notes): aggressive archive sweep of low-value decision records

Archive 21 implemented triplets whose shipped decisions are complete and
whose bodies no longer guide future work (one-off UI chrome, generator
applications whose scripts are self-explanatory, superseded implementation
detail, process history owned by current contracts/skills). Delete 4
rejected triplets whose premises are obsolete: the DeepReadonly proposal
(dev-invariants note now carries the alternative inline), the collapse
tool-owned presentation proposal (superseded by the shipped render-intent
union), retire-mid-turn-steering (steering is now load-bearing across
plan-mode/apiproxy/TUI), and single-session-ACP (automation-only ACP
resolved the question; multi-session isolation is pinned by tests).

Repair every inbound link: retarget intentional historical citations to
archived paths, replace decision-current citations with the surviving
authority, and fix the stale example-execute-over-tsx pointer in
pnpm-workspace.yaml. Re-record pairing sidecars and seal the archive
manifest (append-only; existing seals unchanged).

pnpm-workspace.yaml

@@ -9,7 +9,8 @@ packages:
   # plain-node (`:lib`) boot of any leaf (examples/<leaf>/cordis.yml) resolves its
   # plugins through real package `exports`→lib by walking up to examples/node_modules.
   # Members for DEPENDENCY RESOLUTION only — NOT build targets: tsdown's explicit
-  # globs (vendor/*, packages/*/*) exclude them. See the example-execute-over-tsx Agent Note.
+  # globs (vendor/*, packages/*/*) exclude them. See examples/AGENTS.md and the archived
+  # run-ci-examples-from-built-lib Agent Note.
   - examples
   # Deploy root of the single-exe build: a pure dependency manifest whose
   # closure is what the exe bundles and what the Python runtime distributes.