Slice: Host Jim.edict as an active observer

[flyingrobots]

Slice

Host the smallest Jim.edict application as an Echo-realized active observer
and move production input from frontend operation calls to canonical event
delivery.

Parent: #295.

Minimum state machine

state:
  mode
  cursor
  active_buffer
  pending_action

on KeyEvent:
  request TextWindow

on TextWindow Reading:
  derive a Jim-owned operation intent

on operation Outcome:
  advance Jim state
  emit render projection

Acceptance criteria

• edict/jim/src/Jim.edict owns the minimal persistent editor state and
  transition law.
• Jedit/Bijou/native code normalizes terminal input to a canonical KeyEvent
  without interpreting command meaning.
• Echo delivers the event to the installed observer at an explicit Jim
  basis and budget.
• Jim.edict requests TextWindow.edict, receives a basis-bound Reading,
  and derives any ReplaceRange intent from Jim state.
• Echo executes the compiler-produced generic child program and returns one
  outcome or typed obstruction.
• Jim.edict alone advances mode, cursor, registers, and pending-action
  state, then emits a disposable render projection.
• Jedit renders only the returned projection and performs no optimistic text
  mutation.
• WAL, receipt, reading, Tick, Jim-state transition, and restart evidence
  form one inspectable worldline.
• Negative gates reject TypeScript command-to-operation mapping, native Jim
  planners, handwritten packages, caller patches, and compatibility fallback.

Non-goals

• No broad Vim parity. Prove one canonical event sequence first.
• No application vocabulary or rope intrinsic in Echo.
• No terminal/process/filesystem authority inside Edict.