refactor(packages/coding-agent): simplified terminal transcript rendering

- Removed terminal risk mode toggles from config, terminal state collection, and render controllers.
- Dropped snapshot freezing, thaw tracking, and finalized-block replay in transcript rendering.
- Removed clear-on-shrink settings and initialization hooks from selector and interactive mode flows.
- Simplified render scheduling by using requestRender() without mutation flags or stream checkpoints.

packages/coding-agent/test/debug/terminal-info.test.ts

@@ -19,7 +19,6 @@ const sample: TerminalStateInfo = {
 	hyperlinks: false,
 	deccara: true,
 	screenToScrollback: true,
-	eagerEraseScrollbackRisk: true,
 	synchronizedOutput: false,
 	multiplexer: null,
 	env: { TERM: "xterm-kitty", TERM_PROGRAM: undefined, TERM_PROGRAM_VERSION: undefined, COLORTERM: "truecolor" },
@@ -42,7 +41,6 @@ describe("formatTerminalState", () => {
 		expect(out).toContain("120x40 cells · cell 9x18px");
 		// supportsScreenToScrollback -> the non-destructive CSI 22 J clear.
 		expect(out).toContain("Screen->history clear: CSI 22 J");
-		expect(out).toContain("Eager-erase risk:      yes");
 	});
 
 	it("renders the redraw fallback when screen-to-scrollback is unsupported", () => {