console: intelligent command auto-resolution from user-typed prefix

[havokentity]

Context

Console UX nit: when the user types a prefix that doesn't exact-match a registered command/cvar, the console currently rejects it. The user has to type a longer prefix, hit Tab to autocomplete, then add the args. Friction adds up when 200+ cvars exist.

Goal

Intelligent partial-match resolution at command parse time: if the typed token isn't exact-match, find the BEST prefix match (longest common prefix that's unambiguous) and run that command transparently, with a clear log line showing what we picked.

Examples

> deno metalfx
[console] resolved `deno` -> `r_denoiser` (best prefix match of 1)
r_denoiser=metalfx

> sky proc
[console] resolved `sky` -> `r_sky_mode` (top match; 7 candidates start with `sky`)
r_sky_mode=procedural

> phys_drop_sph 0 1 0
[console] resolved `phys_drop_sph` -> `phys_drop_sphere`
(spawned sphere at 0,1,0)

> r_bloom 1
(no resolution needed; exact match)

When NOT to auto-resolve

If multiple candidates are equally close (no unambiguous winner), fall back to current behavior (error + suggest):

> p
[console] ambiguous prefix `p`: phys_clear, phys_drop_sphere, phys_drop_box, phys_status,
          prim_sphere, prim_plane, prim_light, ... (12 more)
          type more characters to disambiguate

Heuristics

Priority for tie-breaking:

1. Exact match wins immediately, no resolution log line printed.
2. Longest unique prefix (substring at position 0).
3. If tied, prefer cvars over commands (cvars are the higher-frequency interaction).
4. If still tied, prefer the alphabetically-first (deterministic).

Implementation sketch

Single function in src/console/Console.cpp:

struct Resolution {
    std::string canonical_name;   // empty if no resolution
    std::vector<std::string> ambiguous_matches;  // populated when no unique winner
    bool is_exact_match = false;
};

Resolution ResolveCommand(std::string_view typed);

Called from Console::Execute() before the dispatch. If canonical_name is non-empty AND !is_exact_match, print one info-level log line:

[console] resolved `<typed>` -> `<canonical_name>` (top match)

Then dispatch the canonical name with the remaining arg tokens unchanged.

If ambiguous_matches.size() > 1, print the error path (current behavior + list of candidates capped at ~8 with ... (N more) suffix).

Cvar (optional UX)

r_console_smart_resolve (CVAR_ARCHIVE, default 1): toggle the feature for users who prefer strict matching. Off = current behavior. On = the new auto-resolve.

Acceptance criteria

• deno metalfx resolves to r_denoiser metalfx with one log line.
• p (ambiguous) errors with the candidate list.
• r_denoiser (exact match) dispatches with no resolution log line.
• All existing exact-match commands keep working identically.
• New doctest in tests/cvar_ux_test.cpp extending PR feat(console): platform-filter cvar listing + accept "0" as off alias #159's coverage with 3-4 cases (exact match, unique-prefix match, ambiguous, no-match).

Out of scope

• Levenshtein / fuzzy-match across typos (r_denosier -> r_denoiser). Prefix-only for now; fuzzy is a separate issue.
• Multi-word command resolution (we don't have multi-word commands today).

Cross-link

Fits naturally in the same PR as issue #161 (cvar UX: per-value platform gating + dep warnings) since both touch the cvar/command parse path. Bundling them lands the full console UX upgrade as one review unit.