Unify analyzer exit proofs on exception-aware control-flow traversal

[thomhurst]

Follow-up to the design review on #803 (Claude review 5969134517).

ScopeWalker now supplements its graph queries with syntax-based reasoning for loop jumps, terminal exits, catch applicability/order, and constant filters. The focused fixes preserve RESP001 disposal and RESP002 flush behavior, but each new control-flow shape needs additional syntax rules.

Move these proofs onto a shared traversal that models Roslyn control-flow branches together with exception-handling regions and finally continuations. This is an architectural follow-up rather than part of the original #107 loop/switch/coalescing repairs. The current graph traversal already supplies inclusive-start and finally-continuation queries; catch dispatch and correlated branch constraints must be represented before replacing the conservative helpers.

Acceptance criteria:

• Distinguish paths requiring disposal from paths that cannot reach a pending read.
• Model break/continue, return/throw, yield, goto, catch type/filter/order, rethrow, and finally execution without relying solely on lexical spans.
• Preserve all analyzer regressions, including retained versus recreated pending values across loop iterations and generic exception constraints.
• Replace conservative local-goto warnings only where graph evidence proves safety; add positive and negative controls.
• Keep analysis intra-scope and bounded; validate the full analyzer suite.