feat(android): crash reporting, analytics opt-in, settings IA, i18n, open/share/fonts

[willwade]

What

Tier-2 and Tier-3 parity work for Dasher-Android, implementing RFCs 0001 / 0003 / 0006 / 0009. Built on top of \main; full \�ssembleDebug\ is green.

Tier 3 (parity niceties)

• Open file (.txt) via SAF into the output pane. DasherCore has no CAPI to seed the edit buffer (only get/reset), so the loaded text is kept as a frontend prefix and combined with the engine's append-since-reset output for display / copy / save / share (Dasher writes forward).
• Share sheet (\Intent.ACTION_SEND) on the full output text.
• Output-pane font family (System / Sans / Serif / Monospace) + size slider (10–48 sp), persisted in a \dasher_output\ SharedPreferences. Canvas glyph font remains the engine \SP_DASHER_FONT\ param (Customization tab).
• TopBar gains Open + Share buttons (Lucide \FolderOpen\ / \Share2).

Tier 2 (robustness / polish)

• Crash reporting (RFC 0009). New \DasherApp\ Application installs a \Thread.setDefaultUncaughtExceptionHandler\ early; on a crash it writes a \pending_crash.txt\ envelope (exception type, thread, scrubbed stack + engine log tail) and delegates. \lushPendingCrash\ on next launch sends it via PostHog (only if opted in) and deletes it; files older than 7 days are discarded. An engine-log ring buffer (64 lines / 8 KB) is fed from \dasher_set_log_callback\ so each crash report carries what DasherCore was doing. Home-dir paths and emails are scrubbed (RFC 0001 no-PII). v1 is JVM-level; a native SIGSEGV shim for crashes inside \libdasher.so\ is a flagged follow-up.
• Analytics opt-in (RFC 0001). First-run \AlertDialog\ ('Help improve Dasher' / 'Not now') shown when !hasPrompted; no events before the choice. PostHog init moved to \DasherApp.
• Settings progressive disclosure (RFC 0006). Simple/Advanced \Switch\ in Settings filters params on the engine's binary \�dvanced\ flag (Simple is default). A 3-tier (common/advanced/expert) waits on a future \dasher_get_parameter_tier\ CAPI.
• Frontend i18n (RFC 0003). \LocaleHelper\ wraps the Application base context so Compose \strings.xml\ follows the user-chosen locale on every API level (no AppCompat dep). Picking a locale in Settings now also recreates the Activity so chrome re-localises. Extracted toolbar / settings / analytics / output strings to \strings.xml\ with a German (\�alues-de) translation as a pipeline proof. Full string migration + more locales are ongoing follow-up.

Notes

• Commit messages cross-reference the RFCs they implement.
• DCO: all commits are \Signed-off-by.
• Suggested follow-ups (not in this PR): native crash shim, full i18n extraction, RFC 0008 IME-onboarding code.