Allow drafting while commands run

[R055LE]

What changed

• keep the structured composer editable while one command is running
• keep Send and command-history navigation disabled until the shell returns to ready
• preserve the local draft through same-session Terminal switching and Android saved-state restoration
• advance the source candidate to 0.1.0-alpha.7 (10007)
• keep an explicit command queue deferred as a separate product decision

Why

Physical interruption testing showed that recovery was fast, but the disabled composer prevented typing the likely follow-up command while waiting. A local draft removes that friction without adding automatic execution, queue ordering, persistence, or failure semantics.

The transcript subtree previously left composition when switching to Terminal, so simply enabling the field would have lost the draft. A saveable state holder keeps the draft through that same-session view change.

Impact

Users can prepare the next command while the current turn runs. Nothing sends until the user taps Send after the structured shell is ready.

Validation

• focused API 35 test failed before implementation because the composer was disabled
• focused test passes through drafting, Terminal round-trip, failed command completion, saved-state restoration, and exact submission
• ./gradlew --no-daemon test lint assembleDebug assembleRelease connectedDebugAndroidTest
• 70 Android tests completed, with three credential-gated profiles skipped as designed
• release shrinker-contract verifier
• diff check and staged secret scan