feat: add dynamic workspace update parameter editor - #1114

Scope

1. Dedicated Update Workspace editor tab, independent of the experimental sidebar.
2. Reactive REST evaluation for now. Existing receive-only WebSocket helpers are not a drop-in fit; WebSocket transport is deferred.
3. Keep Updating workspace via VS Code fails #1095 separate, including its build-concurrency fix and older-server fallback policy.

Implementation

• Add the shared typed IPC contract, React webview package using existing UI controls, extension panel factory, and extension-owned evaluation/submission session.
• Bind the session to deployment/workspace owner, source build, and target template version. Load stored parameters; evaluate with the actual workspace owner.
• Preserve conditional historical values, reset ephemeral historical inputs, lock existing immutable fields while allowing first-use immutable values, and retain fatal prior-state diagnostics. Validate monotonic constraints before stopping.
• Debounce edits and immediately invalidate stale evaluations using extension-owned generations, since REST response IDs do not echo request IDs. Block pending, invalid, and stale submissions; retain local typing drafts.
• Use exhaustive command/request handler maps and shared IPC helpers. Resend state on visibility/theme changes, bound renderer readiness, and dispose in-memory state on close.
• Recheck source build and target version before mutation. Wait for successful stop, start the exact evaluated version, and verify the resulting build. Never blindly retry an ambiguous build request; closing during stop must not advance to start.
• Keep parameter values out of persistence, CLI arguments, telemetry, and HTTP body/error logging; render descriptions and diagnostics as text.
• Add focused session, panel lifecycle, form, routing, cancellation, and sensitive-logging tests plus Storybook examples; run repository checks.

UI decisions and limitations

• Reuse VS Code-style controls: radio→Select, switch→Checkbox, slider→numeric Input, multi-select→checkboxes. Tag/list input uses a JSON string array to preserve commas within items.
• Show requiredness, disabled/immutable state, diagnostics, evaluation progress, Retry where safe, Cancel, and explicit Update and Restart with a destructive-update warning.
• The sequential stop/start path does not serialize unrelated clients; Updating workspace via VS Code fails #1095 is not closed by this work. Closing after a build starts cannot cancel that server build.