Add tracker:<company> app-list search (#447)

[kasnder]

Implements #447: let users search which installed apps have contacted a particular tracker company or SDK.

What

The existing app-list search box now understands a tracker: prefix. A query like

tracker:gravy analytics

filters the app list to apps whose observed/contacted tracker companies contain the query substring (case-insensitive). Plain queries keep the existing name/package/uid search behaviour unchanged.

How

• TrackerList.getTrackerNamesByUid() — a single scan over the recorded hosts, mapping each app UID to the set of contacted tracker company names (same traversal pattern as the existing getTrackerCountsAndTotal()).
• AdapterRule.getFilter() — on a tracker:-prefixed query, builds that lookup once per filter invocation on the Filter's background thread (no per-row DB queries, no UI-thread work), then keeps apps whose company set has a substring match.
• Discoverability: the SearchView now shows the query hint "Search app, or tracker:company" (new base-English string menu_search_hint only; translations left to Crowdin).

No new screens, settings, or dependencies.

Usage example

1. Open TrackerControl, tap the search icon on the Apps tab.
2. Type tracker:facebook — the list shrinks to apps that have contacted Facebook-owned tracker domains.
3. Tap an app to open its details and see/block the trackers.

Manual verification needed

• On a device with recorded traffic: tracker:facebook (or another company seen in app details) returns the expected apps; a nonsense company returns an empty list.
• Plain searches (app name, package, numeric uid) behave exactly as before.
• The new query hint shows in the expanded SearchView and does not truncate awkwardly on narrow screens.
• Search performance with a large host log (lookup is one DB scan per keystroke after the 300 ms debounce — please sanity-check on a long-running install).

Note: like the "contacted N companies" counts, this searches observed tracker contacts recorded by TC, not static SDK analysis, and interacts with the hidden-app search stubs from 58a9e0a only in that tracker-search matches are restricted to the visible list (stubs carry no tracker data).

Closes #447

🤖 Generated with Claude Code

[kasnder]

Review finding — locale-independent matching (AdapterRule.java): The case-insensitive comparison depends on the device locale. In Turkish, for example, "Branch Metrics".toLowerCase() contains a dotless ı, so tracker:metrics will not match despite the feature promising case-insensitive search. Both the query and tracker name should be normalized with Locale.ROOT. I have prepared that fix on the PR branch.