fix(web): address the review round on the remaining context forms

- `relay` resolves its sender in `contextBody` like every other form. It was
  the one shape whose marker could claim a form the body did not render: an
  unreadable sender fell back inside the body while the row still said relay,
  contradicting the contract this PR's own note states.
- `recall` requires the retained, omitted, and truncated fields. Completeness
  is what the card exists to report, so a reference that cannot state it is
  not a readable recall — showing the label alone presents a confident card
  over unknown loss.
- The snapshot body states the supersession its producer framing line carries.
  That line is the one part of the model-facing text no section contains, and
  unlike an instruction context's `<system-reminder>` it states the form's own
  semantics rather than wrapping content.
- `GoalMessageSource` is a discriminated pair, so `{ form: 'notice' }` without
  its account no longer compiles. The guarantee this PR claims now holds at
  that seam too, not only through `ContextFormed` on plugin sources.
- Goal and tool-goal summaries are bounded by a shared `boundContextSummary`,
  which tool-tasks now uses as well. A goal objective is unbounded caller text
  in exactly the way a task label is.
- The runtime snapshot interpolates once per request: agent-loop renders the
  sections and joins them through `joinContextSections`.
- Every form's fallback branch is pinned, not only the notice one.

docs/cordis-catalog/events.md

@@ -567,7 +567,7 @@ Goal mutation accepted by one live agent. The matching context event is already
 
 Types: [Agent](../core-data-structures/core.md) · [GoalChanged](../core-data-structures/goal.md) · [Scoped](../core-data-structures/scope.md)
 
-Source: [`packages/goal/goal/src/domain.ts:142`](../../packages/goal/goal/src/domain.ts)
+Source: [`packages/goal/goal/src/domain.ts:140`](../../packages/goal/goal/src/domain.ts)
 
 ## `llm/*`
 

docs/cordis-catalog/services.md

@@ -2163,7 +2163,7 @@ async assemble(context: AssembleContext = {}): Promise<PromptAssembly>
 
 Types: [AssembleContext](../core-data-structures/system-prompt.md) · [PromptContext](../core-data-structures/system-prompt.md) · [PromptSection](../core-data-structures/system-prompt.md) · [ToolProviderResult](../core-data-structures/system-prompt.md)
 
-Source: [`packages/core/system-prompt/src/index.ts:310`](../../packages/core/system-prompt/src/index.ts)
+Source: [`packages/core/system-prompt/src/index.ts:322`](../../packages/core/system-prompt/src/index.ts)
 
 ## `ctx.tasks` — `TaskService` (abstract seam)