fix(editor): match IDEA font weights in the light scheme (#35)

Root cause: the editor had no font weight settings, and the WebView rendering of JetBrains Mono looks lighter than IDEA (#32).
Fix (IDEA's Settings › Editor › Font › Typography Settings): configurable Main font weight and Bold font weight (defaults Regular 400 / Bold 700) via --fw-code / --fw-code-bold; colour-scheme bold/regular overrides still win; settings preview updates live. Replaces the Light-only 450/550 hard-coding.
Siblings covered: sticky lines, diff/merge, run console (ANSI bold), Find in Files, completion/parameter info/docs, database editor, debugger value popup, matched braces, terminal with "Use editor font".
Verified: scoped vitest, ide-core tests, in-app on macOS (settings UI, editor weight follows the setting end to end).

Claude-Session: https://claude.ai/code/session_01VUYsdXA2nkF5v6zsC93dpn

src/features/database/Database.module.css

@@ -335,6 +335,7 @@
 }
 .paramInput {
   font-family: var(--openidea-editor-font, var(--font-mono));
+  font-weight: var(--fw-code);
 }
 .formRow {
   display: flex;
@@ -479,6 +480,7 @@
 :global(.cm-openidea-db-doc) {
   margin: 0;
   font-family: var(--openidea-editor-font, var(--font-mono));
+  font-weight: var(--fw-code);
   font-size: var(--fs-code);
   color: var(--fg-editor, var(--fg-strong));
   white-space: pre;
@@ -498,6 +500,7 @@
   overflow: auto;
   padding: 4px 8px;
   font-family: var(--openidea-editor-font, var(--font-mono));
+  font-weight: var(--fw-code);
   font-size: var(--fs-code);
   line-height: 1.5;
   color: var(--fg-editor, var(--fg-strong));
@@ -648,6 +651,7 @@
   max-height: 220px;
   overflow: auto;
   font-family: var(--openidea-editor-font, var(--font-mono));
+  font-weight: var(--fw-code);
   font-size: var(--fs-small);
   line-height: 1.5;
   white-space: pre;