feat(spells): #11 SpellTable - hydrate metadata from spells.csv at startup

New SpellMetadata + SpellTable. Loads docs/research/data/spells.csv at
GameWindow construction (3,956 spells x 11 useful fields including
Family for buff stacking which issue #6 needs). The CSV is copied to
bin/<config>/net10.0/data/spells.csv via the csproj <None Include>
entry; SpellTable.LoadFromCsv resolves relative to AppContext.BaseDirectory.

Hand-rolled CSV parser handles RFC 4180 quoted fields with embedded
commas (the Description column) + escaped double-quotes ("" -> ").
No external CsvHelper dep. Falls back to SpellTable.Empty + console
warning if the file is missing (tooling contexts).

Spellbook now accepts an optional SpellTable in its constructor +
exposes TryGetMetadata(spellId, out SpellMetadata). When the table is
absent (legacy `new Spellbook()` calls), TryGetMetadata returns false
gracefully so existing tests keep passing.

GameWindow:
  - SpellTable field initialized via LoadSpellTable() helper that
    handles the missing-file case + emits the spells: loaded N entries
    log line.
  - SpellBook field constructor-initialized with the loaded SpellTable
    so TryGetMetadata works for the live session.

10 new tests (SpellTableTests):
  - Empty table behavior
  - Header-only loads to empty
  - Single row populates all metadata
  - Quoted Description with embedded commas
  - Blank lines skipped
  - Bad-spell-id rows silently skipped (third-party data is messy)
  - Unknown spell-id lookup returns false
  - ParseRow primitive: simple comma split, quoted-field with comma,
    escaped double-quote.

Total tests: 818 -> 828.

Closes #11. Phase G (issue #6 — fold enchantment buffs into vital max
via EnchantmentMath using SpellTable.Family for stacking) unblocked.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/AcDream.Core/Spells/SpellMetadata.cs

@@ -0,0 +1,44 @@
+namespace AcDream.Core.Spells;
+
+/// <summary>
+/// Per-spell static metadata loaded once at startup from
+/// <c>docs/research/data/spells.csv</c> via <see cref="SpellTable"/>.
+/// One record per known spell id (3,956 entries in the retail dump).
+///
+/// <para>
+/// Used for:
+/// </para>
+/// <list type="bullet">
+///   <item>Buff / debuff bar labels (<see cref="Name"/>,
+///         <see cref="School"/>, <see cref="IconId"/>).</item>
+///   <item>Stacking aggregation (<see cref="Family"/> — only one
+///         enchantment per family-bucket is active; this is what
+///         <c>EnchantmentMath</c> uses to filter out superseded
+///         buffs in <c>LocalPlayerState.GetMaxApprox</c>).</item>
+///   <item>Spell tooltips (<see cref="Description"/>,
+///         <see cref="ManaCost"/>, <see cref="Duration"/>,
+///         <see cref="SpellWords"/>).</item>
+///   <item>Cast-bar audio + animation cues
+///         (<see cref="SpellWords"/> drives the chant).</item>
+/// </list>
+///
+/// <para>
+/// Fields not exposed (yet) from the 35-column source CSV: SortKey,
+/// Difficulty, Flags, Generation, IsFastWindup, IsIrresistible,
+/// IsOffensive, IsUntargetted, Speed, CasterEffect, TargetEffect,
+/// TargetMask, Type, plus 10 anonymous Unknown1..10. Add them on
+/// demand as panels grow.
+/// </para>
+/// </summary>
+public sealed record SpellMetadata(
+    uint   SpellId,
+    string Name,
+    string School,
+    uint   Family,
+    uint   IconId,
+    string SpellWords,
+    float  Duration,
+    int    ManaCost,
+    bool   IsDebuff,
+    bool   IsFellowship,
+    string Description);