Migrate to ClassicAPI for macro display, auras and timing

Squash of the classicapi_next branch (10 commits). ClassicAPI is now a hard
requirement, and the Lua-side reimplementations it supersedes are gone:
net -1087 lines across 12 files.

Macro display: resolved macro actions are published through
C_Macro.SetMacroDisplay, so the client draws macro buttons and the
action-bar function overrides this addon used to install are removed.
Ownership is per macro -- ClassicAPI keeps the macros we never claim.

Auras and timing: ClassicAPI is the source of truth for non-player aura
timing via the positional C_UnitAuras.UnitAura, replacing the write-only
buff tracking tables and the overflow-slot fallback.

Cleanup: the hasPfUI76 flag and the pfUI 7.6 branches it gated, two
silently-shadowed code paths, and per-call allocations in the event and
publish paths (SPELL_CAST_EVENT merged). Packaging moves to
brues-code/packager@vCAPI.

Macro syntax: a clause may carry a leading run of [group] blocks sharing
one action, Blizzard-style -- groups are OR'd, first pass wins, and []
always passes. The ;-separated form is unchanged and mixes freely. @focus
clauses with no focus set now fail quietly instead of printing
"Invalid target" on the way past.

Extensions/MacroErrorUI.lua

@@ -697,30 +697,9 @@ local function EnsureCondHighlightPool()
     end
 end
 
--- Test whether conditionals pass for a given command + alternative text.
--- Returns: true (passes), false (fails), nil (unconditional / no conditionals)
-local function TestConditionalPasses(cmd, alternative)
-    -- Strip ? tooltip hints (irrelevant for conditional evaluation)
-    if string.find(alternative, "?", 1, true) then
-        alternative = string.gsub(alternative, "%?", "")
-    end
-
-    local hasConditional = string.find(alternative, "%[") ~= nil
-
-    -- Dynamic commands: delegate to TestAction
-    if CleveRoids.dynamicCmds[cmd] then
-        local result = CleveRoids.TestAction(cmd, alternative)
-        if not hasConditional then
-            return nil  -- unconditional
-        end
-        return result ~= nil and result ~= false
-    end
-
-    -- Non-dynamic commands: parse and evaluate Keywords manually
-    if not hasConditional then
-        return nil  -- unconditional
-    end
-
+-- Evaluate one single-group clause of a non-dynamic command against Keywords.
+-- Returns: true (passes), false (fails), nil (could not parse)
+local function EvaluateNonDynamic(alternative)
     local ok, action, conditionals = pcall(CleveRoids.GetParsedMsg, alternative)
     if not ok or not conditionals then
         return nil
@@ -745,6 +724,43 @@ local function TestConditionalPasses(cmd, alternative)
     return passes
 end
 
+-- Test whether conditionals pass for a given command + alternative text.
+-- Returns: true (passes), false (fails), nil (unconditional / no conditionals)
+local function TestConditionalPasses(cmd, alternative)
+    -- Strip ? tooltip hints (irrelevant for conditional evaluation)
+    if string.find(alternative, "?", 1, true) then
+        alternative = string.gsub(alternative, "%?", "")
+    end
+
+    local hasConditional = string.find(alternative, "%[") ~= nil
+
+    -- Dynamic commands: delegate to TestAction
+    if CleveRoids.dynamicCmds[cmd] then
+        local result = CleveRoids.TestAction(cmd, alternative)
+        if not hasConditional then
+            return nil  -- unconditional
+        end
+        return result ~= nil and result ~= false
+    end
+
+    -- Non-dynamic commands: evaluate Keywords manually. `[a][b] X` passes when
+    -- any of its groups does.
+    if not hasConditional then
+        return nil  -- unconditional
+    end
+
+    local variants = CleveRoids.ExpandBracketGroups(alternative)
+    if not variants then
+        return EvaluateNonDynamic(alternative)
+    end
+    for i = 1, variants.n do
+        if EvaluateNonDynamic(variants[i]) then
+            return true
+        end
+    end
+    return false
+end
+
 -- Find character offset ranges for each semicolon-separated alternative.
 -- Returns array of { start, finish } pairs (1-based indices within argsText).
 local function FindAlternativeOffsets(argsText)