Allow attachment without the planning archive

[raghubetina]

Removing the optional planning archive after root Compile currently leaves the inherited attach command trying to execute a missing file. Guard both helper locations: prefer the executable root helper, use the executable archived helper otherwise, and succeed without refreshing ports when neither exists. Existing helper failures still propagate.

Reconciles the old draft onto current main 45df3ab1c61d01b444440058cf2f817e3c2e9b9e. It retains the released CLI/plugin 0.6.0 pins and merged preview/Compose guidance. Existing Codespaces retain their creation-time lifecycle commands.

Validation at head 1c1493d1035770ec25f69fd688fbf6164f926b33:

• Pinned Ruby 4.0.5/Node 24.18.0 script/check and git diff --check pass. The old configured command reproduces the missing-helper failure; the new fixtures exercise both helper locations, precedence, absence/non-executability, listener states, and real helper-error propagation.
• Hosted contract CI 35900643361 passes, including built-container checks.
• One disposable Codespace on this exact candidate passed fresh attachment, archived-helper reattachment, archive-present and archive-absent stop/start, archive-absent reattachment with the app running, and private-browser CRUD. Original container lifecycle metadata remained unchanged. The fixture was an exact released 0.6.0 application artifact installed in a recorded layout transition; this was not a new Compile or publication trial.
• Generated application CI=1 bin/ci passed 126 examples with the archive present. A later focused archive-absent Books run had 4 examples / 1 failure: Selenium session creation timed out after the first restart. No retry or source repair was performed. Archive-absent full-system qualification remains unproven; Service #729 owns the immediate qualification remainder. This session-creation failure is distinct from #728 axe timeouts.
• The disposable Codespace was stopped and deleted, verified absent at 2026-09-23 19:07:34 UTC; all 13 pre-existing Codespaces remain stopped.

The bounded provider receipts are handed to the coordinator for Service #730. This does not establish that every older Codespace or future private-port relay incident works without its existing refresh helper.