Seven pointwise fixes on the Orchestration Canvas, each covered by a test:
1. Debounce x chip race: every chip/clear write in OrchestrationToolbar now cancels
the pending search timer first. Left armed, it fired ~300ms later with a setParams
closed over the pre-chip query string and silently reverted the chip.
2. The search input carries an aria-label (searchPlaceholder) — the placeholder alone
is not an accessible name.
3. parseCsvSet trims each token, so `?state=running, failed` parses like the unpadded
form instead of dropping the padded value.
4. toggleCsv was duplicated in the toolbar and the page client; both now import the
single definition from the new model/urlParams.ts (pure, never mutates its inputs).
5. AgentsTab tells "nothing running" apart from "the filter matched nothing": with an
active filter and no work node it renders noMatches + a clear-filters button instead
of the setup CTAs, which would be wrong advice there.
6. Particle cap: orchestrationToFlow stamps `particles` on every edge and turns it off
above PARTICLE_EDGE_CAP (40) simultaneously active edges — StatusEdge then renders
the colored stroke without its 3 SMIL particles per edge.
7. The drawer's error banner clears when an action succeeds, so a recovered failure
does not stay on screen.
Only `noMatches` is added to en.json here; the other locales are task B4.
Refs #12392
3eb16de689