Fix unreplaced placeholders in console messages

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Fixes #118

Problem

The message console showed Found $d labels. with a literal $d in every language. The labels module dispatched messages with three inconsistent placeholder styles:

Message	Placeholder	Result
Found $d labels.	$d	shown literally — no formatter knows $d
Label already defined at line %s: %d	%s/%d swapped	line number formatted as %s, line content as %d (→ NaN)
Label {label} is already used as a symbol…	{label}	shown literally

On top of that, only the GNOME app formatted params at all (via gettext + GJS String.format); the Web and Android apps logged the raw message, so even %d placeholders were never substituted there.

Fix

• Core: unify all message placeholders to printf-style %s/%d (the style every other core message already uses) and fix the swapped specifier order in the "Label already defined" message.
• Core: add a small platform-independent formatMessage() utility.
• Web: substitute params via formatMessage() in all console log handlers.
• Android: translate and format console messages via localize() from @nativescript/localize (which substitutes printf-style params via vsprintf), with a safe fallback to the raw message. Console messages were previously shown untranslated.
• GNOME: no code change needed — gettext + String.format handles %s/%d correctly once the msgids are fixed.
• Translations: migrate msgids and msgstrs in all 15 .po files and the .pot, preserving every existing translation. The German .po had already worked around the bug with %d in its msgstrs; that was kept intact. Android i18n JSONs and the .pot were regenerated with yarn workspace @learn6502/translations run build.

Verification

• formatMessage() checked against all affected messages (singular/plural count, line-number+content, label name, %% escape, no-params passthrough).
• GNOME path smoke-tested in GJS: "Found %d labels.".format(5) → Found 5 labels.
• Placeholder consistency of all migrated .po entries validated by script (each msgstr contains exactly the placeholders of its msgid).
• yarn format, yarn check:format, yarn build pass; type checks pass for 6502, common-ui, app-web, app-android.