Legacy replan matcher treats 'installed' as a stall signal #4336

Problem

LoopX 0.4.3 can classify successful progress summaries containing the word installed as a no_progress_streak and return autonomous_replan_required.

Expected behavior: prose that merely reports an installation must not create a stall signal. Replanning should be driven by typed progress observations.

Actual behavior in 0.4.3: the legacy prose fallback searches for stalled? without token boundaries, so the stalled substring inside installed is treated as evidence of a stalled turn.

Minimal reproduction:

1. Record consecutive progress runs whose bounded summaries include phrases such as CLI installed or package installed successfully.
2. Run the public quota should-run flow for that goal and agent.
3. Observe autonomous_replan_required with a no_progress_streak trigger even though both runs report completed work.

The current stable release no longer relies on this prose matcher after #3161. This issue tracks an explicit regression contract and actionable upgrade guidance for affected installations, so the false positive cannot silently return through a compatibility path.

Root Cause Analysis

The legacy autonomous-replan read model inferred control-plane state from free-form run summaries. Its stall expression matched a substring rather than a complete token, so unrelated words containing stalled could become control signals.

The modern typed-progress design removes that class of ambiguity. The remaining gap is explicit behavioral coverage for installation wording and a clear diagnostic or upgrade path when an affected legacy runtime produces this trigger.

TDD Fix Plan

1. RED: Add a public CLI regression in which two successful progress records contain installed, uninstalled, and installation completed, then assert that quota should-run does not emit a no-progress replan trigger.
   GREEN: Keep autonomous-replan decisions sourced from typed progress observations; if a compatibility text path remains, require complete control tokens rather than substring matches.

2. RED: Add a contrast case using an explicit typed no-progress observation and assert that it still creates the expected replan obligation.
   GREEN: Preserve the typed stall path independently of human-readable summary text.

3. RED: Exercise diagnosis or update guidance for an affected 0.4.3 installation and assert that the output identifies the runtime as stale and points to an unaffected release.
   GREEN: Surface bounded version-aware recovery guidance without interpreting the user's project text.

REFACTOR: Centralize the contract that prose fields are presentation data and typed observations are control-plane inputs.

Acceptance Criteria

• installed, uninstalled, and installation completed never create a no-progress trigger.
• An explicit typed no-progress observation still creates the correct replan obligation.
• Affected legacy installations receive actionable upgrade guidance.
• The regression uses public CLI behavior rather than private helper state.
• All new tests pass.
• Existing tests still pass.