feat: implement target configuration system for issue #1176

Add comprehensive target configuration parsing and inheritance system:

- Create internal/targets package with config structures
- Support JSON configuration loading with inheritance resolution
- Implement multi-level inheritance (e.g., rp2040 → cortex-m0plus → cortex-m)
- Add 206 target configurations from TinyGo for embedded platforms
- Support core fields: name, llvm-target, cpu, features, build-tags, goos, goarch, cflags, ldflags
- Provide high-level resolver interface for target lookup
- Include comprehensive unit tests with 100% target parsing coverage

This foundation enables future -target parameter support for cross-compilation
to diverse embedded platforms beyond current GOOS/GOARCH limitations.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

targets/nintendoswitch.ld

@@ -0,0 +1,85 @@
+PHDRS
+{
+  text    PT_LOAD FLAGS(5) /* Read | Execute */;
+  rodata  PT_LOAD FLAGS(4) /* Read */;
+  data    PT_LOAD FLAGS(6) /* Read | Write */;
+  bss     PT_LOAD FLAGS(6) /* Read | Write */;
+  dynamic PT_DYNAMIC;
+}
+
+SECTIONS
+{
+  /* Code and file header */
+  . = 0;
+
+  .text : ALIGN(0x1000) {
+    HIDDEN(__text_start = .);
+    KEEP(*(.text.jmp))
+
+    . = 0x80;
+    KEEP(*(.text.start))
+
+    *(.text .text.*)
+    *(.plt .plt.*)
+
+    HIDDEN(__text_end = .);
+    HIDDEN(__text_size = . - __text_start);
+  }
+
+  /* Read-only sections */
+  . = ALIGN(0x1000);
+
+  HIDDEN(__rodata_start = .);
+  .rodata : { *(.rodata .rodata.*) }  :rodata
+
+  .mod0 : {
+    KEEP(crt0.nso.o(.data.mod0))
+    KEEP(crt0.nro.o(.data.mod0))
+    KEEP(crt0.lib.nro.o(.data.mod0))
+  }
+
+  .dynsym            : { *(.dynsym) } :rodata
+  .dynstr            : { *(.dynstr) } :rodata
+  .rela.dyn          : { *(.rela.*) } :rodata
+
+  HIDDEN(__rodata_end = .);
+  HIDDEN(__rodata_size = . - __rodata_start);
+
+  /* Read-write sections */
+  . = ALIGN(0x1000);
+
+  .data : {
+    HIDDEN(__data_start = .);
+
+    *(.data .data.*)
+    *(.got .got.*)
+    *(.got.plt .got.plt.*)
+
+    HIDDEN(__data_end = .);
+    HIDDEN(__data_size = . - __data_start);
+  } :data
+
+  .dynamic : {
+    HIDDEN(__dynamic_start = .);
+    *(.dynamic)
+  }
+
+  /* BSS section */
+  . = ALIGN(0x1000);
+  .bss : {
+    HIDDEN(__bss_start = .);
+
+    *(.bss .bss.*)
+    *(COMMON)
+    . = ALIGN(8);
+
+    HIDDEN(__bss_end = .);
+    HIDDEN(__bss_size = . - __bss_start);
+  } : bss
+
+  /DISCARD/ :
+  {
+    *(.eh_frame) /* This is probably unnecessary and bloats the binary. */
+    *(.eh_frame_hdr)
+  }
+}