Fix terminal "Input ready" false positives with prompt detection heuristics + debounce

[Copilot]

The "Input ready" indicator fired unconditionally on process start, any stdout chunk, and any stderr output — regardless of whether the process was actually waiting for user input.

Root causes

• setRunInputIndicatorActive(true) called in QProcess::started handler (before any output)
• Same unconditional call on every readyReadStandardOutput and readyReadStandardError signal

Changes

Detection logic — looksLikeInputPrompt(const QString &text) (new static method)

Three-tier heuristic, checked in order:

1. No trailing newline — most reliable; input(), read, getpass etc. leave cursor on the prompt line
2. Yes/no patterns — [y/n], [Y/n], (yes/no), …
3. Prompt suffixes on the last non-empty line — ? , : , > , $ , # , >>> , ...

ANSI escape codes are stripped before matching so colorized prompts are handled correctly.

Debounce (80 ms)

Instead of activating the indicator immediately on each stdout chunk, a single-shot timer is restarted on every chunk. The indicator decision is made only after output has stopped arriving, eliminating flicker during rapid bursts where intermediate chunks may lack a trailing newline.

Stderr no longer triggers the indicator

Diagnostic/error output is not an input prompt.

Pattern constants moved to file scope

kYesNoPromptPattern (QRegularExpression) and kPromptSuffixes (QLatin1String[]) are initialized once at file scope rather than on each call.

Example — what now works correctly

# Non-interactive: prints lines ending with \n → indicator stays hidden
for i in range(100):
    print(f"Processing {i}...")

# Interactive: prints "Name: " without trailing newline → indicator shown after 80 ms
name = input("Name: ")

New tests

• testLooksLikeInputPromptPatterns — unit-tests the detection function directly
• testIndicatorNotShownForNonPromptOutput — end-to-end: process with newline-terminated output
• testIndicatorNotShownOnProcessStart — verifies indicator stays hidden at launch
• testIndicatorHiddenAfterNonPromptOutput — debounce path, post-process-exit state