Closes #103661

What Problem This Solves

Fixes an issue where terminal snapshots and sanitized agent output exposed OSC title, hyperlink, or clipboard payload text when a producer used the 8-bit C1 OSC introducer (U+009D). The delimiters were removed later, but the metadata payload remained visible as ordinary terminal text.

Why This Change Was Made

The shared terminal scanner now recognizes both ECMA-48 OSC introducers and all three supported string terminators through common pattern constants. The compatibility scanner keeps its historical broad payload behavior, while the sanitizing scanner keeps its stricter payload rules; only C1 OSC handling changes. The fast path also recognizes U+009D so these sequences reach the scanner.

User Impact

Terminal snapshot text and downstream sanitized output no longer display metadata carried in C1 OSC sequences. Adjacent emoji, CJK text, and prompts remain unchanged.

Evidence

• Current-main Testbox repro (4cc5304178): \u009D0;title\u009Cprompt$ rendered as 0;titleprompt$; expected prompt$.
• Regression matrix: ESC and C1 OSC introducers crossed with BEL, ESC-ST, and C1-ST terminators, with adjacent emoji/CJK preservation.
• Focused Testbox proof: terminal-core, gateway terminal, terminal server-method, and bash executor suites; 67 tests passed.
• Post-mutation Testbox proof: terminal-core and gateway terminal suites; 39 tests passed.
• Mutation proof: removing C1 OSC recognition failed exactly the existing C1 sanitizer case plus the three new C1 matrix rows; ESC rows remained green.
• corepack pnpm check:changed passed on Testbox (guards, tsgo core/core-test, lint, and scoped repository checks).
• corepack pnpm format:check packages/terminal-core/src/ansi.ts packages/terminal-core/src/ansi.test.ts src/gateway/terminal/buffer-text.test.ts passed.
• Fresh autoreview: no accepted or actionable findings.

AI-assisted implementation and review.