docs(agents): bring agent-facing docs in line with the R44 fix

Six docs lagged after the post-merge R44 fix added withCapture +
reported-flag.ts. They mentioned withSpan only and described the
capture story as if it were inline in use-case / controller bodies.
This commit aligns them with what shipped.

CLAUDE.md (Key Conventions):
- "Spans applied at DI bind time" → "Spans + capture composed at DI
  bind time" with the withSpan(withCapture(factory)) sandwich and the
  outermost-span ordering note.
- "Capture at throw sites only" expanded to mention the
  __sentryReported flag, the three flag-checking sites (withCapture,
  SentryLogger, RecordingLogger), and where the helper lives.

AGENTS.md (Instrumentation conventions):
- Use case + controller wrapping example shows the full sandwich.
- Capture-rules table now explicitly says "via withCapture" for use
  cases and controllers, and "flag set, withCapture bails" for the
  bubbled cases.

packages/core-shared/AGENTS.md:
- "with-span.ts" entry split into a paired with-span + with-capture
  block, including the actual sandwich code.
- New entry for reported-flag.ts explaining the helper and why
  RecordingLogger inlines the check (boundary rule).
- Barrel re-export list updated.

docs/architecture/vertical-feature-spec.md (§16):
- The bind-production line now describes the withSpan(withCapture(...))
  sandwich, the outermost-span rationale, and the bubbled-error bail.

docs/architecture/dependency-flow.md (TRACER/LOGGER subsection):
- bindAll diagram updated: real repo line annotates inline calls; use
  case + controller lines show withSpan(withCapture(...)).

docs/guides/tdd-workflow.md (Asserting spans and captures):
- Direct-injection example shows the binder sandwich.
- Capture-assertion example explains the flag-bail behaviour and
  links to the new tests/r44-no-double-capture.test.ts e2e example.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docs/architecture/dependency-flow.md

@@ -112,8 +112,9 @@ apps/web-next/src/server/bind-production.ts (bindAll)
         │     ├─ blogContainer.bind(TRACER).toConstantValue(tracer)
         │     ├─ blogContainer.bind(LOGGER).toConstantValue(logger)
         │     ├─ ArticlesRepository(config, tracer, logger) → bound to IArticlesRepository
-        │     ├─ withSpan(tracer, ...) wraps every use case → bound to UseCase symbol
-        │     └─ withSpan(tracer, ...) wraps every controller → bound to Controller symbol
+        │     │     (real repo: inline this.tracer.startSpan + this.logger.captureException per method)
+        │     ├─ withSpan(tracer, ..., withCapture(logger, ..., useCase(deps))) → UseCase symbol
+        │     └─ withSpan(tracer, ..., withCapture(logger, ..., controller(uc))) → Controller symbol
         │
         └─ (same for auth, marketing-pages, navigation, media)
 ```